I just came off a 29er (Yeti SB95) and am now on my first 27.5 (Transition Patrol). I'm 5'11", FYI. The 29er rolled slightly better over rough ground, but the 27.5 just feels right for some reason. The Patrol is longer travel, yet I'm closer to the ground; the bike just feels more maneuverable and natural (I've been riding MTBs since the 1980s, so I was extremely used to 26" wheels).
One thing that was important to me was BB drop; I like the BB lower than the hubs. I never get the feeling of being tossed over the bars. The 29er was good, this particular 27.5 is great (Patrol). I find myself, at 47 years old, doing things I've never done before on the Patrol. Sure, it doesn't roll as fast, but at my age I'm not winning any uphill KOMs.
I'm sticking with 27.5, but won't ever rule out 29ers.