-
What sort of riding do you want to do in terms of time spent climbing vs time spent descending? Do you think you'd want to do some bike park days? Would you like to ride any downhill trails/ freeride stuff?
For the most part the likes of a Jeffsy will be all the bike you'll need in terms of suspension travel. Modern suspension geometry is so good that 140mm will soak up almost anything if you're a decent rider with the exception of the very burly freeride/ downhill stuff.
For wheel size it largely comes down to the following stereotyped description. 27.5 wheels are more playful. 29 wheels are faster.
“Do you want 27.5 or 29 wheels?
Do you want a hardtail or full suspension?”
No idea