Ike beats them all w/ the exception of Spence Jr. That might be a 50-50 fight. His jab isn't as solid as ike's but it's still very good.
Crawford would box his ears off and Spence would beat him pretty easy too, I feel Ike would be too powerful for the other 3 though, Thurman was badly hurt in his last bout and Ike was a puncher.
He spanks Danny and Porter. Love Keith but he cannot decision this man. Crawford would have a hell of a time with that bazooka jab. Hell of a time. I think Crawford squeaks by him, just like DLH did, but that is probably my recency bias speaking. Spence has the physicality to hang with Ike, but I dunno if he has those skills that would be necessary. Another squeaker either way. 50/50
I have to go with Quartey By default. Haven't seen Spence or Crawford fight any good welterweights to make me think they are better than Quartey. Lets put it this way, the only reason why Quartey isn't rated higher is because he was competing against ATGs. Todays welters do not have that kind of opposition, and Ike would probably be the best WW today.
I think he beats all of them but Spence. Ike's resume is pretty damn impressive. Wins over Vince Phillip's, Oba Carr, Jose Luis Lopez, Verno Phillip's and he should have won against Vernon Forrest. Losses to Oscar and Fernando in very close competitive fights and to Winky. No one ever blew him away. Too bad he had so many long layoffs and missed out on fights with Tito and Shane. He very well could have ended up in the hall of fame had he won a couple more fights/titles.
If Oscar, Forrest, Winky, Vargas, Lopez, Carr etc. Couldn't "box his ears off" I doubt Crawford could. Not saying Crawford couldn't win but no way he does it easily. Quartey would be a handful for any WW in any era.
He almost definitely would lose to Spence and Crawford, but would be favored over the rest. Thurman would have a good chance if he could regain his form. Old Pac might pull it off. Pac does well against that style.
Quartey was bad ass as a WW. Great bazooka jab, good countering skills and heart of a lion. He would a top 3 WW right now.