boosters

annular or down leg

down legs are the least restrictive.

annular booster mix the fuel better than the other down/stright/etc boosters.
Annular boosters are a lil more restrictive only due to size in a comparable down leg same 'cfm rating' But they size the venturi to compensate, so it is what it is 'cfm' wise but with better mixing/spread of the fuel/air.jmo

It's on the big side of cfm 'per build' where you will really see the annular shine while the down leg becomes per say 'lazy' response wise.jmo