When comparing Amazon S3 vs Dropbox, the Slant community recommends Amazon S3 for most people. In the question“What are the best website hosting providers?” Amazon S3 is ranked 11th while Dropbox is ranked 16th. The most important reason people chose Amazon S3 is:
The free tier will cover most personal home pages.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Free for small sites
The free tier will cover most personal home pages.
Pro Easily scalable
There's no cap in storage or traffic. Cost is based on usage.
Pro Super cheap with a year's worth of free service
S3 storage costs $0.03 per GB and gets cheaper the more is stored, PUT, COPY, POST, or LIST requests are $0.005 per 1,000 requests and GET and all other requests are $0.004 per 10,000 requests. And with some restrictions is available for free for a year.
Pro Fast setup
You can provision a S3 bucket, upload files, setup the DNS, and go live in under 10 minutes.
Pro Fast
S3 is fast even without a CDN.
Pro Easy to setup with CDN
Simple to set up with Amazon's CloudFont CDN.
Pro Supports custom root domains
To set up a custom domain, Amazon Route 53 has to be configured as the DNS provider with the domain registrar, two buckets have to be created and configured with the name the same as the domain - one including, one excluding www. A more in-depth explanation can be found here.
Pro No security risks
There's no server to manage, so no security issues to patch or keep watch.
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
Cons
Con Credit card needed
Amazon will try to retrieve the money every month after one year trial. If you have no money you will be banned.
Con Setting up automatic public permissions is confusing
By default, S3 sets uploaded files to private. You can configure your S3 bucket to auto-apply public permissions by copying and pasting a template. But the template might be intimidating to some users.
Con Confusing web interface
Amazon S3's web interface is quite confusing, especially for first-time users, but there are many tutorials online that help beginners to set up a static site on S3.
Con No SFTP support
Amazon S3 does not have SFTP support, instead the S3 web interface has to be used.
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.
