Hmmmmmm...
I think Xenoblade Chronicles is the best one overall, simply because of the quality of the source material. That being said, it's the same experience I've already had. The sidequest tracking is a nice feature (despite the fact that I still find the sidequests dull), but other than that it's just an audiovisual update, which I generally wouldn't buy. Mainly bought it for future connected, so hopefully that part delivers.
FFVIIR on the other hand isn't as good as either Xenoblade DE or the original, but it does offer a new experience compared to FFVII. I'll avoid better or worse for the sake of this topic, but different itself can be a good thing.
So... basically... if I had a time machine, and could go back in time to tell myself which game to buy this year (for whatever reason my past self can only buy one) I'd advise him to buy FFVIIR, and play Xenoblade again on the Wii (my opinion may change depending how good future connected is, but based on what I've heard I don't expect to be blown away). On the other hand, if I were going to recommend a game to a person who hasn't played the originals or the remakesters, I'd probably recommend Xenoblade DE.