BG1 did everything better than BG2. Everything [
link]. Moreover, the campaign was developed in parallel with the
engine, making it by far the greater creative, technical and organizational achievement by then-fledgling developer, BioWare.
BG1 was
seminal: it sparked the
RPG Renaissance. It is the greatest D&D-based RPG of all-time and the
fourth greatest RPG of all-time whereas BG2 is a monstrous distortion of the gold standard in classic AD&D adventuring set by BG1.
BG2 recycled so much from BG1 (as sequels often do), but it didn't add much substance on its own. It didn't invent anything, it didn't innovate a damn thing [1]. It is bigger and more feature-packed, but worse off for it. BG1 proves that less is more.