For me at 6’5” tall, Santa Cruz has nailed their sizing. I’m on their XXLs and love the sizing. I’m truly in the XXL for clothing which just makes sense. The reach, stack and STA of my Hightower 2 is spot on for my height. They seems to have found an great balance so that the front end stays planted on all but the very steepest climbs, the STA is slack enough that I can put power down well, and the reach/stack combo gives me a balanced riding position.
I’m eager to try Specialized’s S6 sizing which is their XXL whether they want to admit it or not. It looks to be a touch bigger than SC’s XXL so I’m curious to see if I’ve finally reached my limit and have bikes that are truly big enough.