My two big criteria are

• the frame works with 2x drivetrains. I have grx di2 11 speed in my parts bin, and running it with 46/30 or 50/34 rings and an 11-40 cassette is fantastic IMO
• it can fit 2.1 schwalbe thunder burts on a wide internal (~30mm rim) while still running 2x

Other nice to have options would be

• suspension corrected geo (or at least a ~400mm fork axle to crown)
• somewhat aero shapes
• udh
• bsa or t47bb

... all of it should be fine

If you need to know more about this frame AMA