When comparing Dropbox vs SmugMug, the Slant community recommends Dropbox for most people. In the question“What are the best file sharing services?” Dropbox is ranked 9th while SmugMug is ranked 16th. The most important reason people chose Dropbox is:
You can use Dropbox via website, by installing a desktop client that creates a folder that you simply drag and drop files into, or with their mobile app. Everything synchronizes across all devices used and cloud storage. And Dropbox offers easy methods of sharing whatever is within it.
Specs
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Pros
Pro Easy to use
You can use Dropbox via website, by installing a desktop client that creates a folder that you simply drag and drop files into, or with their mobile app. Everything synchronizes across all devices used and cloud storage. And Dropbox offers easy methods of sharing whatever is within it.
Pro Cross-platform desktop and mobile
Dropbox is available on iOS, Android, BlackBerry, Windows, OS X and Linux. By having a client for so many OS's pretty much anyone is covered no matter what kind of device or OS they are using.
Pro Allows sharing a folder
Using a desktop client: right click on the folder you want to share and select Dropbox > Share This Folder, then enter the e-mail addressees of people you want to share the folder with.
Pro Smart updates to big files
If a small portion of the file is changed it sends/receives only the differences (not the whole file), which is fast and bandwidth-efficient.
Pro Allows sharing a single file via link
Whether using desktop client or web interface, simply right click on the file you want to share and select Dropbox > Share link, then send the link to the people you want to share the file with. The recipient does not require a Dropbox account.
Pro Up to 18GB of free storage space
Dropbox personal accounts start out free, with 2GB of space, but users can get extra space by recommending the site to friends, or taking part in events like "Dropquest", where users can win extra space by solving puzzles.

Pro Linux support
Dropbox offers native Linux support, integrates with Nautilus file manager.
Pro Reliable
Pro Desktop client has no file size limit
As long as you have enough storage available, you can upload files of any size using Dropbox desktop client.
Pro Folders can be downloaded compressed to save bandwidth
To save bandwidth and download speed you can choose to compress a folder into a zip archive for download.
Pro Adjustable bandwidth use
To not slow down the network or save traffic you can limit the upload and download speeds of Dropbox.
Pro Lots of addons and integrations
There are official and third-party Dropbox add-ons that extend the functionality of the service and add ease of use of existing features.
Additionally, Dropbox can be integrated with existing applications to bring its functionality to other apps.
Pro 30-day version control
Dropbox keeps deleted and earlier versions of files for a month.
Pro Instant disaster recovery
Your files always synced online means instant disaster recovery. When your hard drive becomes unbootable, pick up another laptop and just carry on with your life from where you last saved.
Pro Available free storage can be increased with referrals
You get extra free space for you and your friend if they sign up.
Pro Fast sync speed
Pro Easy to use, powerful website customization options
By simply dragging and dropping various content blocks (such as menu, galleries, social buttons, text) around it's possible to quickly and visually lay out the site. Customization options are context aware. So, if a gallery is open, gallery customization options will be shown, if a page is open, page customization options will be shown. To change the look of the site there are multiple themes available that can be further customized by changing HTML & CSS.
Pro Good SEO
SmugMug automatically pulls photo metadata such as keywords, descriptions and captions, and inserts them in appropriate places in the webpage so that search engines can properly index them. If that information is not set before uploading, it can be added via back-end as well. Also in the back-end it's possible to set site-wide metadata and custom URLs to further optimize.
Content still needs to be dispersed via social media, blogs, forums, etc for it to show up in search results, but SmugMug has a well polished codebase that takes search engines into consideration and won't hinder content's exposure potential.
Pro Intuitive drag & drop backend
SmugMug has a drag and drop interface that allows organizing photos into folders and galleries, adjusting how they're displayed, setting privacy preferences, editing meta keywords and descriptions, etc in an easy to use manner.
Pro Galleries and folders can be password protected
A gallery or a folder and it's sub-items can be given a password that will be asked when trying to access them.
Pro Reasonable commerce options with fair sales commission
It's possible to sell digital downloads of photos and videos as well as prints. SmugMug takes 15% of profit on sale.
Pro Visitors can be allowed to upload photos
Anyone accessing a gallery using a specifically crafted URL can upload photos to it.
Pro Good branding options
Watermarks can be added to photos, printmarks to prints, and branding can be applied to orders (shopping cart, thank you prints and stickers).
Pro Engagement and feedback tools
Photos can be shared, commented on and liked.
Pro Business account users can set passwords that give access to the backend
It's possible to set an assistant password that gives access to the backend (with some limitations). Very useful for letting someone trusted upload and arrange photos. The assistant won't be able to delete photos or galleries, customize the site or access private folders.
Pro Custom domain support
To use a custom domain a "Power" pricing tier or higher is required.
Cons
Con Too little free space
There is just too little of free space available comparing to the competition.

Con Not secure
They don't apply end-to-end encryption, files are visible to admins, governments, etc..
Con No privacy
Extensive collecting and distribution of user data to commercial third parties.
Con Consumes a lot of CPU resources when syncing many files
Con All-or-nothing (non-selective) upload
Uploading generated contents (cache, compiled code, etc.) is prone to conflicts, wastes bandwidth and free space.
Con Low bandwidth
Con Dropbox keeps deleting features, chasing customers away
For instance, all photo albums got deleted. It used to be very easy to share a couple og photos, now it's PAINFUL and must be done file by file.
Con Nocive development model
Takes a lot of decisions that usually damage community, from deleting features to making impossible to use with other filesystems than ext4 because they decided without a plausible reason (they said it was about xattrs, but all modern linux filesystems supports xattrs, so it's bs.)(they remove this later, but it's too late).
Con Problems when synching between Linux and Windows devices (unconfirmed)
This summer I lost thousands of files due to this problem on older projects which subsequently needed revising and had to be rebuilt as tons of the source was gone.
Con Restricted only to 3 devices for FREE accounts
Recently dropbox decreased the number of linked devices to 3, so you can't have more than 3 linked devices. This is problematic if you use Dropbox to sync between your computers.
Con Can unintentionally delete your files if you reinstall your OS without closing Dropbox
If you reinstall the operation system for your PC and you do not close Dropbox, it will delete all files.
Con Can't designate self as print provider
Con Lacks an integrated blog system
