People do seem to hark on about this rather too much I think. It just goes to shower to power of marketing.
IME, yes, there are differences between wheel sizes, but IMO the differences are relatively slight and over-emphasised. I’ve ridden different brands of 26er bikes that are more different than some 26ers and some 29ers that I’ve also ridden
I ride 29ers now, I prefer the way they ride. For me, its the extra composure they seem to have, and the extra grip that they can give on techy climbs. YMMV.
650b feels no different to 26 last time I rode one.
Test ride the ones you’re curious about, buy the one you like.
Biscuit?