When comparing Notion vs Obsidian md, the Slant community recommends Notion for most people. In the question“What is the note taking app for Amazon Alexa?” Notion is ranked 10th while Obsidian md is ranked 30th. The most important reason people chose Notion is:
To-dos in Notion aren't just dot point lists. You can drag and drop them into columns just like Trello (Kanban style), you can have sub-tasks, and you can easily mark things off as completed so they are no longer in your way. Notes are also powerful, with proper formatting and ways to manage and search for them, which makes it a great Evernote alternative.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Does a great job with both notes and to-dos
To-dos in Notion aren't just dot point lists. You can drag and drop them into columns just like Trello (Kanban style), you can have sub-tasks, and you can easily mark things off as completed so they are no longer in your way. Notes are also powerful, with proper formatting and ways to manage and search for them, which makes it a great Evernote alternative.
Pro Unlike anything else
One of the most complete applications one can use to build a personal dashboard (or professional) and migrate all other services to it. No more calendar, task, notes, financials, lists, writing and wiki apps, just Notion.
Pro Awesome for wikis
You can easily start writing a bunch of web pages, share it with co-workers and choose whether to publicize or keep your contents private. It's also easy to hyperlink pages.
Pro Full-featured on desktop, mobile and web
Even the right-click menus on the web are the same as the app.
Pro Pages within pages within pages, to infinity
You can have a ridiculous amount of information within a single note. Look at how it works, you'll be surprised!
Pro Blocks offer incredible flexibility
The basic unit of organization in Notion is the block, which can be a chunk of text, an image, a bullet point, or even a link to another page. Each page consists of these blocks, which can be easily reorganized, moved to other pages, converted into other content types, or generally manipulated in many useful ways. Because of blocks, restructuring information in Notion is way easier than in any other wiki or notebook app.
Pro Flexible contents storage and organization
You can upload files and embed online stuff in any hierarchical structure using pages, toggle lists, etc.
Pro Highly visual, with icons next to every new page and so on
This feature makes it very easy to find certain notes and such. And great for visual people as well. You could also add images as icons instead, if you like.
Pro Quick and effective search
Just type in a word and you'll have results in no time at all.
Pro Cross Platform
Works with Android, iOS, Windows, & Mac OSX
Pro Amazing view flexibility
You can create different views for a page's content and easily toggle between kanban, table, etc. (As long as the content is able to allow different views.)
Pro Less headaches when editing pages
Lets you restore your page to a past edit. Also works with sub-pages and databases. Though it is worth mentioning that it's a paid feature.
Pro Great spreadsheet functionality
You can use calculation/formula, links, attachment, inter-referencing of data from other pages or tables, embed documents and images in the table cells.
Pro Attach files in tables
You can attach files in table cells, which is a feature missing in most spreadsheet-like applications.
Pro Renders Markdown Syntax
Add code blocks, Headers, bullet point, numbered lists, or To-Do boxes by typing using Markdown Syntax (instead of klunkily moving the mouse to formatting boxes)
Pro Locally stored, not dependent on cloud
LOG¹⁰
Pro Fast growing
It's becoming more powerful everyday, it seems like they add many functions within several days.
Pro Lightweight and very customizable
Pro Backlinking
This allows you to link notes back and forth really easily.
Pro Helps visualize personal knowledge in ways nothing else allows
Pro Markdown makes for flatter learning curve
Pro In-line tagging
Ability to tag-as-you-write and find each occurrence of a tag in the entire vault makes it very easy to organize and retrieve notes.
Pro Very easy to use and link notes, preserves the standard form of markdown
Linking notes is a game changing feature. Very easy to use and link notes. Their implementation of markdown doesn't deviate from the standard form of markdown and so the same files can be used by other markdown programs without any consequence.
Pro Multiple Vaults
A Vault in Obsidian is like a database. Internal links and files are not shared across Vaults. Each Vault is opened with a separate instance of Obsidian. Each Vault can have its unique app settings and plug-ins. Useful if you have distinct/unrelated projects or "data spaces" requiring different workflows and data relations.
Pro Infinite panes, split panes, lock panes
In Obsidian, pane = window = note = page
Obsidian allows you to open as many notes as you can fit concurrently in your screen. You can split a pane horizontally/vertically. You can lock/link panes so they scroll in sync, useful for and edit & preview modes.
Pro Cross-platform: works on Linux, MacOS, and Windows
There is no mobile app yet.
Pro Daily Notes with template
Daily Notes plug-in, when clicked, generates a new note with the current date. Great for journaling and reduces friction in your writing habit.
You can create a custom template for your Daily Note.
Pro Functionality extensions with a growing number of plugins
Also open for anyone to develop their own extensions/plugins.
Pro Intuitive and easy to use with an excellent help system built-in
The app doesn't frustrate the user - the built-in help is excellent.
Pro Random note
A plugin that, when clicked, surfaces a random note from your vault.
Pro Markdown rather than outline/blocks
Pro Slides for giving presentations from within Obsidian
Easily turn your notes into simple yet sleek powerpoint-style presentations by enabling the Slides plugin and adding the --- separator.
Pro Readable as it hides the [[ ]] around links when in Preview mode
This is a big difference, as having to read through long-form texts laden with [[links]] gives friction.
Pro Great onboarding experience
The onboarding consists of well-written help documentation (saved as a vault) served in small chunks and organized systematically so that you become familiar with all its features as well as get hands-on experience in real time.
Pro Page previews on hover
When you hover on an internal [[link]], you get to preview the note without opening it on a new pane.
Page preview plugin must be enabled.
Pro Multiple cursors
A feature unseen in other tools.
From the help doc, "This can be useful when modifying a lot of lines in the same way, for example putting - at the beginning of multiple lines to turn them into a list, or appending [[ to a series of links you’ve copied from elsewhere."
Pro Vim key bindings
Can switch on or off Vim key bindings in the editor settings.
Pro Community of developers building themes and plug-ins
Due to the tool being very developer-friendly, there are tons of cool developments being made to it by 3rd party devs.
Pro Support for tags
Pro Can copy search results and paste as lists and/or links in a new or existing note
Pro Not locked to a provider
No lock-in to a certain company - just markdown files on disk.
Pro PDF viewing within the app
PDFs are directly embedded in the markdown preview.
Cons

Con no true backup
true backup can only exist if it's automated and easily recoverable. else, it's just an outdated copy or useless scrambled data.
Con Designed with teams in mind, and less formatting than Evernote.
Evernote may be more individual-oriented and has more formatting and such options available, but whether that affects you is down to personal preference. Try both and see which you prefer.
Con No lightweight tables like Markdown
Every table is some sort of database with a default view and every row is a data set with attributes and it's own page. Simple tables as in Markdown are missing.

Con not yet a new protocol, as it could be! (or could it?)
think of scuttlebutt or email. the best evernote alternative would be a "web 3.0" of sorts. something that would be just a simple file added to a computer and automatically replicated to other computers along with a website. and any company could easily pick up the concept and make their own hosting, including some awesome google drive/host of sorts.
Con Not always very intuitive
Column filters are not that intuitive to apply.
Con No mobile app
Though it is right now in the development and you can basically use any other markdown editing apps till then.
Con No WYSISYG editor yet (like Typora)
But it's on the backlog, though.
Con No ability to add dates that link to a daily note, when that day/note may not yet exist
(You can create a backlink which doesn't yet exist; it just doesn't auto-fill for you)
Con Proprietary software lock-in
Creates dependence on the application with the promise that the content is yours but that cannot be entirely true without the application being free and open source software. You will end up altering the way you create the content to take advantage of Obsidian features and your processes will evolve for its workflows. This replicates the lock-in pain that people experience moving their highly personal information from one proprietary platform to the next when that initial platform stops serving them well, goes out of business, or becomes a bad actor.
Con Still in beta
Con No table editing yet
(Available as a plugin).
Con Pretty new software
At this moment there is a limited amount of resources / howto's available.
Con Requires .md files
Can't read .txt or other plaintext file formats. Can't read asciidoc files.
Con Needs to be polished
They still need time to fix some bugs.
Con No cool kid cachet to boast about at meetups
Built By the Slant team
Lustre recommends the best products at their lowest prices – right on Amazon.