I find BG series more compelling for the RPG aspect, but I really love how IWD handles combat...it is far more gamey in BG. Really, are you going to have a party find one monster, then run away, kill that one monster they found, then repeat until the bad guys are sufficiently weakened? That doesn't even seem to fit the intent of combat encounters in RPGs...so I think that is something BG got wrong. This tactic is not possible in IWD, as the AI actually decides to alert other AIs if it sees a character in your party. That said, I miss the NPC character, which isn't really present in IWD but is overflowing in BG.

IMHO, they are complementary...but they do both fill different roles. If BG could be made to have less gamey combat, that would be even better!

I think the tacic you describe is only possible in the unpatched, vanlilla version of BG1. I remember it annoyed me so much that I send in my tank to "activate" the whole enemy group before, giving them a fair chance before ruthlessly killing them.

I wish that were the case...that tactic actually still works that way even in BG:EE. I will occasionally get someone else following me, but nothing like in IWD. In IWD, you get the whole encounter, whether you retreat back or not.