My vote counts for 6billion, and I say get neither of those games! (evil laugh)
Seriously though, I personally didn't like either game. Mario 3D land is just a rehash of older games (but what Mario game isn't these days?), and I'm one of the few who HATED New Super Mario Bros. I also couldn't bring my self into Kid Icarus. I sold that within a month if I'm to be honest. The controls didn't bother me (I enjoyed Metroid Prime Hunters after all), but the gameplay... Eh...
I admit I may not like something others do like and the other way around too, and I'm surely not about to seriously say "Get neither else you're an expletive" in a fanboyish manner. I subscribe to the "To each their own" philosophy, at least when it comes to games. If you're not about to crap all over stuff I enjoy, I most certainly wont be doing to same to yours. I may defend my self, but nothing more.
On to what I recommend. Really, there's not much I can recommend. If you want a long game, Tales of the Abyss is the way to go. If you want something you will sink hours into arcade style, Starfox 64 3D is your ticket. Want to relive the past with a remake of an awesome game? Ocarina of Time 3D is what you need. Tetris? Don't get Tetris Axis if all you're going to play it for is the Marathon mode (instead get Tetris Party on the eshop). Want a shooter? Gah, I don't think there are any, at least none like CoD. Maybe someday.