Interesting discussion. I feel Campbell is the greatest I've seen play for us, he was nothing short of colossal for us for at least five years. iirc he was in the team of the tournament at euros/WC three tournies in a row, in an era of amazing CBs.
Toure sort of lives on in his halo a bit though. He was an incredible athlete at his peak and was superb the year of the Invincibles, but much less of a defender than say, Koscielny, who tends to get less flowers, largely as a result of playing in a team with Hleb and Adebayor, rather than with the likes of peak Vieira and Henry.
I think Gabriel and Saliba are our most complete CB pairing ever, if not individually the best we've had. I don't think any of the previous pairings were tested to the same degree as they are - the standard in the PL is so high now. In the 90s the best forwards tended to play in Serie A and La Liga, and probably still La Liga in the 00s, but nowadays it's fairly well split between La Liga and the PL. I think the changes in European competition also mean we get see Gabriel and Saliba going up against tougher opponents more consistently than previous eras too.
I'm not convinced by the protection argument, Gabriel and Saliba have to do so much sweeping up against incredibly quick and powerful forwards. Wenger's best teams also had world class defensive shields in midfield and some very hard working players like Freddie. Both sides are/were comfortable sitting deep but also spent a lot of time camped around the opposition box. Between current inverted fullbacks, overlapping fullbacks back then and Vieira/Rice joining attacks, I'd say it's at least wash between the two in that regard.
Adams/Bould/Keown were perfectly adapted to their era but I'm not convinced that even with modern training they'd be as suited to the modern game.
