First off, wonderful! Continue to contribute to such great causes as Chui's works.
The SNES4All cover looks just fine. However, the text seems to be a bit big. The text also doesn't seem to add anything to the cover itself. It seems just to fill up space. If you were to get a direct quote of Chui or quotes from people comparing DC SNES emulators, it would seem more professional. Also the word "alternative" seems to set it aside in not necessarily a positive connotation. SNES4All doesn't seem like it "alternatively" does anything different than other SNES emulators. For "Cover Designed by GXB", it looks kind ot trashy. Instead of having the ESRB rating, since this isn't officially rated by the ESRB, why don't you make yourself a professional looking GXB Cover Design that is simple and artistic. Eventually if you get good enough at cover design, emulator scenes will want you to design work for them. That could eventually set you up (with enough practice) to design commercial works. Also, you could set the background to artistically blurred screenshots of other SNES games (not including Nintendo related titles like Mario/Wario/etc.) and set the logo brighter with even a slight glow around the edges so the logo doesn't blend into the background. Also, the SNES4All logo at the top right seems a bit redundant. Overall, this one is the better of the two.
The AES4All cover... You could take a lot of the same comments I made for the SNES4All covers and apply them to the AES4All cover. It seems that your sprites need to be cleaned up a little bit. Everything is fine except for the "4" and the "S". The text also doesn't bring anything special to the cover design. I think the general AES4All logo is a GREAT start, but it needs some more creativity. There is a lot of artwork available on the internet, and if you are creative enough to start something like this, you could probably sketch a few ideas out on paper. Maybe ask yourself to dream about some cool logos at night and sketch them in the morning. *shrugs* The AES4All isn't pleasing to read since it breaks rules of Western eyes. Take the SNES4All logo for example. It's simple, good-looking (but not amazing,) and it really adds something to the emulator. Try messing around with Illustrator to bend and stretch some fonts until you like something. Or you could take the basis of the Metal Slug font and completely redraw them and then do something cool with them like that. Your possibilities are almost limitless. I think it's a good start and it's almost complete.
Other ideas: You could design Chui a logo... Like taking his avatar and putting his name on it or something. Who knows? This could go next to Sega, along with SNK and Playmore. (Even Nintendo.)
These are just some suggestions, but ultimately it's up to you.