Yep that’s a tough one.
I swore by 29" to the point that I was calling it the ultimate uni - the only one to keep in other words - because I found it so versatile here in Paris: good for city riding because fast yep maneuverable, great for my forest riding (flat-ish XC really), so I decided it should my only muni in the US. And whilst that was true in NYC, I realised that it wasn’t great in NC. Took it to Lake Norman last summer, and the wheel proved to be a bit too big for the rooty uphill parts we encountered. And then I rode it around the family house, and found out that the wheel is too small for suburbia riding.
Might get a 26" wheel to turn it into a more appropriate muni next summer.
I’d aim at the 26", and keep an option on that 29" in the summer. There’s no such thing as too many unis…