I think you have to care about all three. Some think extreme water lift is the sole answer to vacuum performance. Its a balance of both lift and cfm.
The guys stringing 3-400' of hose regularly want high lift blowers not venting at 14" Hg at the worst spot... at the tank decreasing cfm to the wand. The average Joe stringing a hundo for residential doesn't need water cooled 20" Hg, just good operating lift over 10" Hg at the wand. Blowers with big shoulders have no problem transmitting lift and cfm over distance when setup right and using bigger diameter hose in the first few legs of the run. These same guys need 250° at the machine to keep even 180° at the wand on these long strings.
Many moons ago we use to clean a hospital section that we only used the TM for solution line and used the portable with an apo with 50' of 2" to extract (pumping out into a brute can on wheels) that moved with the portable. Much better performance, speed, setup and breakdown than the TM could do alone at ridiculous hose runs with way better dry times. The carpet was in house interim bonneted with old school pH 11 bonnet cleaner and didn't require prespray, just water to prespray and good to go with no foaming in the tank, cleaned up fantastic. Had plenty of cleaning power already in the fibers lol