My personal faves, from best to worst:
1. Gradius Galaxies -- One of the best-looking GBA games with that classic Gradius flavor. Remember to play on higher difficulty, that's where the fun begins
9/10
2. Iridion 2 -- Real close with Gradius Galaxies as my favorite. Simply amazing graphics and music, this game pushes the GBA to the LIMIT. Real cheap, too. 9/10
3. Steel Empire -- Artistically, it's beautiful and more vibrant than the Genesis original, but it's losing something that the Genesis had...still, it's fun and very nice. I wouldn't pay more than $30-$35 for a complete one, you might be getting ripped off. 8/10
4. Phalanx -- Port of the SNES original with a new intro and whatnot. I actually like it quite a bit, even if it is simple. Graphics are nice and it's basically dumb fun, a time-waster. 7.5/10
5. Darius R -- WHAT THE FUCK HAS HAPPENED TO MY DARIUS SERIES...3/10