At 154 I agree. At 147 hes a little too frail to be optimal. I still have no idea why he came in at 145 against Leonard. It makes no sense. Hearns wins anyways.
I would default to Hearns but to be fair I think a lot is still to be determined as far as Spence goes. It's hard to say at this point who he is or what he's capable of on the most Elite level.
Tommy would put a devastating beat down on Oscar. Floyd and Pernell Whitaker would off necessity give Tommy a chess match. Pac-Man would get iced as he would jump into that devastating right cross. Very difficult almost tantamount to impossible to beat Tommy at Welterweight.
Floyd would be crushed by Hearns with remarkable ease. At 6'1" and 78 inch reach Hearns will just shoot the right hand over the top of Mayweathers shoulder and crush the hell out of him. Hearns would absolutely and totally destroy Mayweather.