Baldur's Gate 2 is the reason there was so much hype for Baldur's Gate 3. It's considered one of the best western RPGs of all time and often included in the list of greatest video games of all time.
BG1 gets a lot of nostalgia shoutouts but BG2 had significantly better storytelling with a lot more actual choices to make and much more in-depth character interaction. Also, the voice lines weren't quite as repetitive or obnoxious.
Also the plot of 1 and the way it presented itself was just... janky.
Personally I thought the overall plot from 1 was better because it kept you guessing "what is really going on" till close to the end where 2 basically told you what was happening in the opening sequence.