Maybe I'm being too harsh on the 3x7 drivetrain because most people will likely ride on the middle ring anyway. However I read even if it's a 7 speed cassette and not a freewheel, a 7 speed freehub won't take an 8 or 9 speed cassette.
The other alternative would be a 2x8 speeds with a 40/28 crankset and 11-36T cassette. (Even though manufacturers would likely go 46/30 and 11-34T.) That would give a larger range plus the fact I heard a double front derailleur can be easier to adjust than a triple. My issue with a 46/30 crankset which I've already tried is when I changed to the 46T ring I'd usually downshift one gear in the rear because of the huge jump from 30T to 46T. That issue is gone with a 1x. (Another issue is having to choose which ring you want to ride on.)
Another alternative would be 1x9 speeds with a 36T crankset and 11-40T cassette. Even though I know manufacturers would likely do 38T and 11-34T cassette. You might be limited on the top end on the first choice but I don't have an issue not going above 90 gear inches.
You know what might be a good choice for most people (who don't want to spend too much)? The Kona Dew 2 has a 40T chainring in the front, an 11 to 45T cassette, a Shimano Rapidfire shifter and Tektro hydraulic disc brakes (even if I prefer V-brakes or mechanical disc brakes). Anyway, that would give you around 24 to 100 gear inches without having a front derailleur. It also has large tires and front (for Racktime Topit) and rear rack eyelets.