Saruman for or against Sauron?

[Kuruharan]

I believe that this could be achieved by the way Elrond/Galadriel would have tried: large armies with absolutely subservient generals.

Nope. The West was militarily incapable. Try to fight Sauron this way and you are still playing to his strength. They couldn't have won like this, they would have had no time.

I don't think that killing Sauron by 'mere' warriors is out of the question, seeing that it had already happened once at the end of the second age, in direct combat.

Sauron was not killed by "mere" warriors. He was...well, actually something surprisingly ambiguous happened considering the magnitude of the event, by two of the greater beings that had ever walked on Middle-earth and they died in the process. This actually only reinforces my point that these armies aren't going to be able to keep Sauron from making a beeline for the Ring.

I believe that said ringlord would have avoided direct confrontation

And as I said, I don't think they could avoid it as long as they stayed in Middle-earth.