Bailly is being done a disservice being named in nearly everyone's team. We've only won 4 trophies all decade and he was key in two of them, started the League Cup final under Mourinho and was in the Europa team of the season if I'm remembering correctly - generally looked very good that entire season, and the thought was that he was a very promising young CB. Injuries ruined him since, obviously, and we should have got rid ages ago.
I'm actually struggling with center backs, because we haven't signed too many and even the relatively crap ones like Bailly / Lindelof / Maguire have had moments. Most of the truly bad ones were kids thrown into the deep end by LVG, or the old guard (Evans was garbage under Van Gaal, ditto Smalling in his last couple of seasons with Mourinho).
I'd go:
Valdes - Onana is off to a shite start but I back him to turn it around. This guy barely got on the pitch and still managed to piss everyone off on his way out
Darmian - looked amazing for about three games. Then just ... pointless
[placeholder CB - will think of someone]
Rojo - one good spell of form in his entire time here, and even that was with the caveat that he got away with at least 3 straight-red challenges in about two months)
Telles - I'd read he was an incredible crosser and set piece taker when we got him. Must have produced, like, one assist in his time here
Schneiderlin - self-explanatory
Schweinsteiger - see above
Van de Beek - and again
Sanchez - must still be the worst of all time
Sancho - might end up beating Alexis at this rate
Falcao - was completely shot when we got him, beats Weghorst/Ighalo because they were desperate punts