it may just be the nostalgia speaking, but i think bg1 is better than bg2 in the vibes department.
2 is better mechanically, has better items, the classes and stuff are better, but... (of course, some of this doesnt apply to you since you're probably playing the enhanced edition)
2's villain is shit and the story is bad. 1 is childish and b-movie level, but still better IMHO.
also, the pacing. in 2, you're thrown out into a big city immediately after the too long intro dungeon. in bg1, the big city comes at the end, you start out finding lost dogs in the forest and shit.
no idea about 3, i'll probably never bother to play it. i'm too at this point.