Which Game Should I Buy?

Well I've saved up some money lately, enough to buy a Wii game, and I'm tossing up between two games, Super Paper Mario and Super Mario Galaxy.

Super Paper Mario

Price: $40

Genre: RPG

I want this game eventually, and it's on sale somewhere, I can't remember. Apparently it's quite long, and the dialogue is just as funny as Paper Mario 2: TTYD. Also, I don't have an RPG on my Wii yet, and this seems like the best one available.

Super Mario Galaxy

Price: $85

Genre: Platformer

This game is more expensive, but apparently very good, and GS gave it a 9.5. The game is fairly long, and looks superb on the Wii. I've also heard some music from the game, and it's also excellent, like the rest of the game, according to my friend.

Suggestions please, because I really can't decide between the two, thanks.

Archibald_83