NSMB2 is so disappointing, I bought it near launch... finished it in about 6 hours....

NSMB games just aren't worth it if you've played any of the others, they all use same assets, they're all the same.

Get Xenoblade, it'll last you many times longer.

While Xenoblade is by far the best of the two, I want to show some love for NSMB2. It's a great platformer on its own. It's pretty fun and it probably has the most replayability of any 2D Mario ever due to the coin factor alone. Sure, even with that gimmick it's still pretty generic and if you have played every NSMB then it will feel most of the same, but on it's own, it's not bad at all. The opposite.

Xenoblade, one of the best games ever made on any system.

If you already own Xenoblade on Wii, there is not much of a reason to buy it on the 3DS. They didn't add any content (aside from figurines you can buy with play coins). Unless you love the game so much that you think you'll be playing through it several times, and you need it with you wherever you go, then no need to buy it.

New Super Mario Bros 2 is what it is. It's a fun and well crafted platformer. Coin rush mode is a nice addition that adds replay value. If you liked the other games in the NSMB series, you'll probably like this one, even if it is not quite as good as those.

Xenoblade hands down (i have both)

If you like LOOOOOOONG jrpgs, Xenoblade for sure. If you eant a game you can throw in and play for 10 or 20 min, probably NSMB2. That said, of you're open to both, Xenoblade, absolutely no contedt.

Xenoblades if you havnt played that before... is a much better game imo.

Definitely Xenoblade...
Xenoblade was really incredible on a big screen, but it's not as if it's unplayable on a handheld...
And as somebody who works 45 hours a week with a 90 minute commute, having the freedom to play it anywhere is pretty major...

Well I already stated that I've already play both on Wii. So my reason for purchase is to play on the go obviously lol. I just want to know which one is worth enough for double dipped.

This answer my question the most. But,

The power of playing Xeno on the go is something I couldn't resist. Seems I just have to hold my purchase until more deals incoming.

Buying New Super Mario Bros 2 wouldn't be double dipping.  It follows the same format as the other NSMB games, but the levels are all entirely different, there are different power ups etc.  It's a sequel.  A formulaic sequel, but a sequel nonetheless.