I began by playing Baldur's Gate 2 and then, some years later tried BG. And to be honest, the vast areas full of nothing were quite exhausting. I have played BG2 many times through, but BG1 only once. The reason is simple: the quiet areas are a burden, it's not really fun anymore. Of course that is even underlined by the lack of NPC interaction, but even then I really wouldn't want to see the same repeated.
On the other hand, I enjoyed a lot playing IWD and IWD2. While I'm not certain if it can be said to have "exploration" outside of the main quests, the wilderness in those two games touched me very deep. Because of that I vote for the middle option.
