Xenoblade Chronicles stands up to me as one of the Wii's most polished titles and probably the best JRPG ever made. The story was surprisingly solid for the genre (even after localisation), the soundtrack is top notch, the world is HUGE and the gameplay was really well done; all 7 characters in that game played differently while remaining reasonably balanced. What makes the title really amazing for me though is that even with the graphical eyesores that came about because of the wii hardware limitations, the world remained immersive and breathtaking from start to finish.
With those hardware drawbacks now gone with the Wii U, it leaves me pretty giddy to think of what monolith are going to do next. From what we've seen it's looking to be somewhat similar to Xenoblade (which is a VERY good thing), so even if it was an HD makeover of everything Chronicles had to over, that would be fine by me.