Gearing is all going to depend on your fitness and how much you value small jumps in gears. I still haven’t made the switch on any of my bikes because I get a lot of use out of the low gearing, and I’m not necessarily obsessed with having the latest and greatest when a 2×10 works just fine for most riding I like to do. When parts fail and I need to upgrade, it might be worth it then, but for now, no biggie.
29 is kinda where it’s at now though. While 26 is great and there isn’t anything wrong with it, replacement parts like tires and wheels will slowly become harder to find over time if you want the latest and greatest tech.