But the best Infinity Engine game is definitely Planescape: Torment. Even after all these years, no game even comes close to it.
PS:T is fantastic, but it's a very different beast from the BG games due to the limitations and advantages of having a protagonist with a very definite story. If I think of modern RPGs I'd compare PS:T to in feel and ambition, I'd be looking at something like Disco Elysium. Which I do think comes close and even is maybe better.