I would recommend to play Xenoblade Chronicles first, and I wouldn't recommend to play it on 3DS. A game with such a beautifull world design deserves to be experienced in a big screen and without any graphical downgrades, and 3DS versions is definitely worst in terms of visuals (and controls). So get the digital game for Wii U and prepare to enjoy the best RPG of the 7th generation. And then you can move forward to XCX ;)

Buy both xenoblade x and xenoblade on Wii u as everyone here has suggested. Personally I liked XCX more that. XC but that's up to the person playing it. In terms of quality both are amazing games but remember when playing Xenoblade Chronicles that you have to grind a lot. So fight the monsters you see and keep upgrading. The thing that ruined XC for me was when I did not do that and the story enemies would just kill me. I tried to upgrade but fighting the same monsters again and again got boring and I tried like 59 times to progress in the story but nope. Now i don't remember where I stopped and was thinking of finishing it on the WiiU since I have the game in my system got it for 10 dollars combined with XCX for 50

XBC on WiiU VC.

Haha yeah I got stuck grinding for hours only to not get past the area I was stuck at. Probably just going to watch Chugga's LP of it eventually because I'm not going to just pick it up again 60+ hours in but there's no way I'm playing those 60 hours again.

You should only play Xenoblade Chronicles Wii, it is a much better JRPG in every aspect. If you like the genre, you will love this game and it may become your all time favorite game on any system. Best way to play is in 1080p on Dolphin Emulator, 2nd best way is Wii-U VC.

https://youtu.be/rH7YPm3eogY?t=480

Xenoblade X however in my opinion is not really worth playing (I wasted over 100 hours), it is not even a real JRPG and feels more like some kind of dungeon crawler without dungeons but with mechs and a very bad and extremely short main story. It takes all the bad but optional fetch quests from Xenoblade and makes them mandatory. It also limits your party choices and once a mission is started, you are locked out from the rest of the game until you complete it. And it offers nothing besides the main city, all the continents are empty and lifeless, there is not a single town or city to explore.

Play the original so you can play Xenoblade 2 when it comes out

If you can find the original Wii copy of Xenoblade Chronicles 1, do yourself a favor and SNAG IT.
A few years ago, physical copies were going up to over $100... and they announced the New 3DS version, and those prices dropped like a rock, thank God.