There are a couple of things to understand: the first is the cable pull effect. The work done is the same but you can either get there by:
1) Lots of pull, low force
2) Short pull lots of force.
This is all about cable tension (less is good, less squish of outers, less lost to friction) vs. enough travel at the brake end to close the pads and have something left over. The critical thing is that the force necessary at the caliper needs to suit that available down the cable.
Least pull was needed by calipers and wide pull cantis, especially if the straddle cable was kept short.
Low-pro cantis needed a bit more pull (DiaCompe made a special road lever, the 287)
V's need lots of pull (DiaCompe again helped with the 287V along with Tektro / Cane Creek)
Long pull levers (like V's) will not give enough cable force at the brake end, will feel very firm but that's because they can't apply enough force to do anything useful.
Short pull levers give lots of force at the brake, but may lose over the cable run. They can feel squishy as the high cable tension means they can squeeze hard on everything down the line - but they often run out of travel.
Shimano has been fiddling round with pull ratios for its road calipers, which means later ones need longer pull. This is for 10-11-12 speed, so beware, the levers have subtle differences. These may not work as a result with Avid BB5/7 road brakes.