Vermaelen and Koscielny seem quite similar to me. Koscielny's got better, and though he still looks too rash at times, I'm pretty happy with his recent form. For me though, Vermaelen's easily one of the best defenders in the league, and when he's fit, you find a way of fitting him into your team.
He and Djourou look, on the surface, like a good pairing to have.
