Class(es) that get most/least mileage from BiS

[Solist]

From a class doing the class job in purely 1+1=2 sense... Monk by far. The way mend scales with gear is fairly broken. Warriors are a very close 2nd however. Nothing scales like warrior/monk mitigation thanks to broken lack of AC softcap here.

For a class to radically change its potential I'd agree with Gats that it's druids. No one class totally changes the potential of what is possible like a druid geared properly.

The least scaling class would likely be wizard. Nothing matters to a wizard except shissar elementalist's cane in raid scene or rend robe out of raid. Without those items you're about 4 or 4.5dps different when EC geared vs absolute BIS and max possible FT.

Everything else is just more survivability really. Enchanters in full BiS survive more often on breaks, they gain exactly zero power. Some HP regen etc yes with 10th ring etc. Shamans are much the same, you slowly pick up a few more mobs you can kill outright at peak turtle/defensive play efficiency and DS pots with max velious AC. A shaman in velious gear just kills stuff faster than one in kunark gear as you can afford to let torp drop for a tick per minute incrementally more often with every 50-60 worn AC increase.

Everything else is just par for the course really, your potential doesnt change, you just get better at what you've always been able to do.

Classes without their VP game changers vs with is the real discussion. VP is the defining zone for most classes.