Mosley De la Hoya Vargas Forrest Trinidad Mayweather Cotto Margarrito Pacman (now and or at the time of cotto / Hoya/Mosley etc)
If we are talking everyone at their peaks. Crawford gets KO'd by Mosely, De La Hoya, Forrest, Trinidad, and maybe Pacquiao. He beats Cotto, Vargas is a 154 pounder, and Crawford hasn't fought at 154 yet to my knowledge. I think Crawford would outbox Margarito, wide decision, and lose to Mayweather by decision. Spence would get KO'd by Mosely, De La Hoya, Trinidad, Forrest wins maybe by stoppage, probably by UD, not sure about Vargas, as Spence hasn't fought at 154. Spence would beat Mayweather by decision, grind down Cotto, and win by stoppage. He'd beat Margarito by decision, probably beat Pacquiao by decision as well. I recall Spence being hurt by Kell Brook. Oscar, Mosely, and Trinidad, all punch harder than Brook, and I'd say Forrest punches at least as hard as well. All those guys were skilled enough to touch Spence up more than Brook, and Danny Garcia did. They also punch harder.
I don't think Spence has the power to keep a younger Pac off him. I think present day Pac would have faired better than Garcia, on stylistic grounds.
They'd be competitive with all of them but I'd favor both of them to beat Vargas, Forrest and Margarito
Prime Pacman over Crawford, Spence and Floyd in their primes. Such tough specimen with high workrate. Not coincidence that nice king Floyd picked up Pac to fight with when he was enough old. Prime pacman like beast from hell.
They both lose to Mosely, De La Hoya, Mayweather, Pacquiao, Tito and maybe Cotto. I'd pick Spence and Crawford over Margarito and Forrest. I don't know how they'd perform at 154, but I think both are better fighters than Vargas.
They lose to everyone save for Margarito. Cotto and Forrest stand a chance but don’t believe either could pull it out. I’m still not sold that Spence is back to the Spence of old. Something was off vs Garcia.
I'd favor De La Hoya, Trinidad, Mosley, Forrest , Pacquiao, and Mayweather over both at 147. Spence has a better style to beat Forrest than Crawford with his workrate and pressure IMO. Mayweather would really negate Spence's volume and be too sharp offensively provided we're talking about the Floyd pre-Maidana when his offensive timing/sharpness really declined. I think Crawford edges Cotto in a great fight by exploiting Cotto's vulnerabilities up the middle. Once he adjusted, he could continue the success Zab had very early in the fight. And I think Spence beats a back-footed Cotto down the stretch to edge a decision in a fight where Cotto probably leads 4-2ish after six. Cotto definitely had the timing and skill to explot Spence's and Crawford's defensive holes, though. Both would be highly competitive.