Ditto to Todd in general. Hard to anticipate everyone's needs in a brief post, but here goes . . .
Low roof pros: better access to parking garages, drive-throughs, country roads and especially rural driveways with low overhanging tree limbs and branches; will not "stick out" visually as being taller than most cars/SUVs; stealthier for short-term urban overnight camping in parking lots etc.; better MPG.
Low roof cons: ditto re: headroom; difficult to put bed in back for short-term stealth camping and be able to stand to dress. Been there and done that in old Econoline with a more flexible back.
Hard not being able to stand up, stretch and straighten out the spine.
Medium roof pros: Todd -- too many uses to ignore. Will support owner-built-in-stages mini RV, while still being OK as around town everyday vehicle with one bench seat behind driver/passenger; better visibility for Wagon passengers looking out while driving on a sight-seeing tour, cross-country drive, etc..
Medium roof cons: sticks out visually; looks like a delivery truck; harder to stealth urban camp; may preclude certain drive-throughs, trestles, overpasses, garages and roads/driveways with low overhanging limbs/branches; lower MPG.
I am aiming to pull a small RV trailer, so the low roof is attractive, but I will need to drive and sit in one with seats and windows to feel comfortable making any decision.
Good luck to all!