Welcome to the new and improved Proflex / K2 Tech Forum!
I like XTR M950/952 series stuff (especially the low-clamp front derailleur with the hinged cage). You can still find stuff in good condition, but it goes for a fraction of the original cost now, especially on eBay. It's tough and very light, even compared with modern X.O. If you end up buying a crank, though, I'd stay away from the ones where the spider and big ring were a single piece, and instead look for one of the versions with the separate 5-arm spider (or buy a cheap XTR crank and fit it with the Middleburn 4-arm spider specifically for this crank). That said, any crank would work well...I really like Race Face Racerings chainrings...great shifting. - Doug