Absolutely Cling, I agree with virtually everything you're saying, Maldini could go in either left or the centre and be a perfect choice. He is marginally better as a left back though and pretty much the consensus greatest of all time, let alone the CL era!
My only comment originally was that Nesta is the best CB and I don't think that is controversial, there is a few candidates but he's the best player IMO, slightly ahead of the likes of Maldini. We wouldn't be able to have the same debate with left back though because Maldini is so far ahead of all the opther option - it is undisputed.
Does that make sense? I think he is absolutely brilliant and if he had somehow made it down to 14 (never would have happened) I would have picked him first choice and over any other defender - including Nesta - so I am not trying to criticise him at all.
Whether or not he is better at left back is definitely a trivial argument, but so many football arguments are!