I'd definitely suggest Psychobuff for meleers if you're ok with using Chems. 8 minute duration (24 if you take Chemist, which certainly did) with +25% damage, +3 strength (more damage), and +3 endurance (better chance to make it to melee, which means more damage). Definitely one of the better long term buff options. Apply Fury (+50% Melee Damage, -5 Perception, Short duration) when necessary to really blow things out of the park.
I've had a damage value for a super sledge (powerful legendary trait - so 25% boost there) at over 1000 fully buffed. Could one shot anything short of a extra large (Behemoth, Mirelurk Queen) or the Supermutant Masters with the deeper HP reserves, usually Legendaries. Humans absolutely do not survive a swing.