I guess I'll be the lone asshole and make a case for Pea here.
Though it's close as hell either way.
There's one big mark against Leonard that hasn't been mentioned yet, and that's his inactivity.
He may possibly have the bigger single achievements than Pea (namely his comeback win over Hagler), but Pea continually took on all comers all through his career. Leonard spent half his career inactive, then sporadically coming back, grabbing a title, and then disappearing back into retirement.
I also happen to think Pea as a lightweight was one of the most complete fighters I've ever seen, perhaps every bit as much as Ray. Ray probably had more natural talent, but Pea was a much better technician IMO. He even could punch pretty good at that weight.