Anybody else notice that everything from Baconsoda's post up is from a year ago?
Definitely 4.84 stats back then, which put the Level 4's as the strongest Transport class turrets.
Another thing that people often forget to account for is shot speed, which helps increase the chances that a shot will hit its target at closer ranges. (If the shot gets there faster, the target has less time to dodge.)
Last I checked the Transport Turrets all have higher shot speeds than most, if not all, the fighter-class turrets.