NOTE: Post here saying the Virtual Console is better and it will get deleted. I don't want any bickering over other systems in this thread.
So yeah I've come to love the Xbox Live Arcade just as much as the real games themselves. This is the place to discuss games you've purchased/tried and would recommend to people or tell them to steer clear of.
My 3 favorites are:
Marble Blast Ultra: I don't know what it is about this game but I am crazy for it. I've already beaten it through and through and will probably do so again. Buy it. Now.
Boom Boom Rocket: The game's kinda easy, but it puts a very unique spin on a very strong franchise and I enjoy playing it just for that. I'd recommend it if you're into rhythm games, but it might not be your thing if you're not.
Geometry Wars Retro Evolved: I was rather skeptical about this at first, not being much of a fan of games like Asteroids and other shmups. But this has an amazing game concept that blew me away when I first played it, and it's got replay factor like you wouldn't believe. Definitely worth the purchase.