So, we played through the prologues of both BG1 and PoE and this is what he thought about them. There's a caveat, however, he's not that much into RPGs, he likes action games more. With that said:
Character creation: He thought that PoE's attributes were more complex than BG1's. He said the skills (lore, mechanics etc.) were a bit weird to be apart from the attributes. He understood them, though, so it's not like it's confusing to the point of being unable to figure them out.
Aesthetic: Pillars of Eternity is much more colorful and has a bit cheaply engaging SFX, more for younger audiences (think kids) and reminded him of arcade games. It was a bit too much for him. He said that he doesn't think that's bad, just an observation. The models are a bit stale and not expressive, kind of like made of plastic, they could use more life-like, let's say, "animations".
Interface: He thought the UI of PoE was a bit more categorized and compartmentalized, so it made it easier for him to use.
Combat: He played a Mage and Wizard in BG1 and PoE respectively, and PoE wins hands down because of more things to use at first level. The combat flows more smoothly as a result and you interact with the game more during combat.
Prologue: Here's where I was surprised at his insight. He thought that Candlekeep was a better prologue because it contrasts more prolonged peaceful times with sudden battles that surprise you.
Writing: BG1 wins because the dialogues were more naturally flowing and they represented normal human interaction, as opposed to PoE where things are explained AT you. You aren't a part of the conversation in PoE, just there as a non-entity to be talked to. He thought the story hook was better in BG1, i.e. when Sarevok kills Gorion.
Final verdict: In the end, he thought that he'd like to continue both, but he was more interested in finishing Baldur's Gate first.
