Great call on Braxton. I was going to say Duran, as well, and I am glad you mentioned Braxton/Qawi, it is too easy to just default to Duran for these kind of questions, because it got me to think instead of just going with a default answer. JCC Sr would be another choice for me.
Duran followed by Armstrong. Honourable mention to Tyson who for such a squat stocky tank of a man had excellent head movement.
Tyson and Duran were both aggressive, but they weren't necessarily pressure fighters in most cases. They weren't the types of guys who 70-80 punches or more per round consistently.
Duran and tyson were not really pressure fighters. Tyson's cus d'amato style was unconventional, kind of an aggressive counter-puncher at his best. Duran was just a masterful all rounder who often had to pressure opponents who ran at LW
Maybe at LW but he was VERY impressive with his boxing skills at higher weights which is why I don't consider him a pure pressure fighter.