TES is a weird series for me since I started on the Gothic side of things. By the time I gave TES games a try there was always something blocking me from enjoying them in full. Not that any of them are bad, they just didn't shape my tastes like other games did.
I actually started writing a full post going in detail about all of the titles I played but the truth is all I want is a modern Daggerfall with a big modding scene. That would be my dream come true in terms of sandbox fantasy RPGs.