Memedroid is the best of all of them for several reasons:
1. It provides a really beautiful interface.
2. It let people interact by means of a system to vote and comment.
3. It provides comics from several resources in English, Spanish and Portuguese.
4. It allows to store your favorite comics and see it whenever you want.
5. It let read comics even with Internet.
5. There are a system for ranking users.
The other rage readers just let read comics and that's all. No interaction, no vote system, no comment system, no comics without Internet.
In a nutshell, If you really like rage comics I recommend you Memedroid.