I am struggling to understand why most of the comments here are generalising this issue. I have never ridden 650 but I’ve had a few 29er and 26ers. The difference between how my solaris rides in comparison to say my first 29er(Chumba HX2) or my GF bitter to my last 26er(C456) are so significant that to say “29ers are good at **** or 26ers are better at ****” just doesn’t make sense at all.
IMO the only people that can begin to justify statements like that are the ones who have ridden a selection of long/short travel suss and hardtail bikes in both 29 and 26 inch wheels, as a wild stab in the dark I don’t think that there are too many folk other than employees of bike mags that have this experience to comment upon(Although there are a couple I know personally).
If you haven’t done that don’t misinform people with mis/preconceptions, ego padding and wishful thinking.
Trying “all 3” doesn’t immediately mean you can call it on which is best only which one was best for you and even then that opinion is formed having only tried maybe 5% of the bikes out there.