Proctor and Beneva. The cycle takes about three minutes and at least two minutes of that (I have timed it repeatedly) are for Beneva traffic going straight. This is despite the fact that Proctor is one of the busier east-west routes through town.
Honore and Bee Ridge can be pretty awful too, though I don't think it's quite as bad. Still, Honore traffic doesn't get nearly enough access.
Cattlemen and Bee Ridge is also terrible, but at least it allows traffic going all directions about equal access.