Baldur's Gate II remains my favorite RPG. It took the first installment of the franchise to a whole other level, adding more depth in many domains such as the amount of spells and animations. The game had better quests and a smarter scenario. It also gave more importance to NPCs, creating romances and improving their personality. And Jon Irenicus, the antagonist, is, to me, one of the best villains in video gaming history.
Of course, Pillars of Eternity was a great game too, but it is many years late. It's not as groundbreaking as the Baldur's Gate franchise. But it certainly has the BG feel to it. The scenario tries to be a little too complex for its own good at times, and some dialogues are somewhat cryptic. The main issue, to me, is the lack of personality of the characters who accompany you on your quest. There is something missing. Many of them are one-dimensional.