Andengine (opensource), not happy with it, had to build tools and stuff from scratch, took a lot of time, didn't know the free version of unity allows you to create games for android, damnation....
Thank you JindoBlu...
If you want to improve the graphics, why don't you try blender ?, I'm not a designer but it kind of help me a lot, besides it's free, very well documented, very easy to learn and you can create awesome designs in a short amount of time...