[quote name='gambitmachete']Sonic is good, but get Drill Dozer. It's a shame it's getting overlooked due to lack of name recognition. It's the best 2D platformer since Yoshi's Island, IMO.[/QUOTE]
The Yoshi's Island comparison is a pretty big leap, since that's one of the very best platformers I've ever played in all my years of gaming, but it is indicative of the love for Drill Dozer from people who have gotten into it.
I was amazed and delighted by Drill Dozer. I felt like a kid again, rocking some SNES on a summer day when I should've been outside. Fun play mechanics and level design and a surprisingly good challenge. GAME FREAK deserves a lot of credit for this one.
Anyway, Sonic DS is arguably the best Sonic game in about a decade. If you remember the fun of the early Sonic games, you'll probably really like Sonic Rush. The sense of speed is wonderful and that feeling of being just on the verge of losing control is great. I thought the level design got slightly weak in a few areas, though, and the multi-player lost its fun after a short while.
All in all, I'd go with Drill Dozer. Sonic Rush is really good, but it does feel slightly played out. Drill Dozer feels fresher to me.