There are tons of free and not so free image hosts on the internet. There is an image host for just about every niche, purpose, and person. If you're looking for a free image host you have plenty to choose from. But the question is, is one image host better than another? While this can be pretty annoying, the answer to that question is: "the best image host" is subjective based on what you need. What I may need an image host may be completely different from what you need one for.
There are many reasons why someone may need a free image host. Sometimes someone needs to distribute a picture quickly among friends. Sometimes someone may need to post a picture on a forum and the only way to do so is by "hot linking". Sometimes you want to put a picture up on the internet anonymously without it being tied to your existing MySpace or PhotoBucket account.
Online image hosts are of every shape and size. They aren't created equal. Each host will have their own pros and cons and be able to do certain things better than others. One major factor that goes into an image host is their cost. While many declare themselves as "free", sometimes that definition can be very loose. Many major image hosts like ImageShack or Photobucket require you to register an account to use the majority of their hosting features. While they did say they're "free", it actually costs you a bit of your privacy to use their services. If you're someone who doesn't like giving out your name and email to every website out there, it's best to skip those sites. Of course, with all the free websites, there are a few image and file hosts that actually cost money to use. These sites are designed for people looking for a place to safely store their data. These websites usually allow you to store unlimited amounts of pictures, documents, and other files for days where you lose your computer's data due to a virus or other disaster. If you're looking for that type of service, paid hosting is the way to go.
Another major difference between many online image hosts is the amount of data you're allowed to store on their servers. Some hosts will limit how many people can look at your picture or limit how big of pictures you can store on their sites too. The reason why many image service providers do this is to lower costs due to bandwidth. Bandwidth can end up costing image hosts thousands of dollars each month and so to cut back, they limit.
So if you're still wondering what host would be best for you, you should start checking out image hosts and using them yourself. If you try one site and don't like it, find another. Image upload sites are a dime a dozen and so you have plenty to pick and choose from.