In IWD the adventurers literally meet at random in a Tavern, the ultra-classic generic DND start.
The main reason I love IWD is because the mechanics of ADND 2e are very well suited for the type of combat the game offers. I made a mod to fix some of the more egregious issues with the game (like the extremely cheesable Resting system), and as a result the gameplay is actually quite good overall. Since you will be spending most of your time fighting, it makes for quite a good dungeon crawler.
BG, on the other hand, while it has mostly the same mechanics, largely focuses on NPC interactions and story beats. The combat is usually relegated to random encounters and dungeons, none of which hold a candle to the combat encounters in IWD, with a significant number of them being randomly generated forest critters that drop small amounts of gold and not much else. Most people who like BG don't mind this because they aren't playing the game for the combat or the gameplay (which is made very aparrent by Planescape: Torment players, where the gameplay is largely meaningless and mostly non-existant, you can't even die), and instead focus on the story. That's fine too. I just find the story extremely badly written and most of the characters very annoying. I want to punch Amoen nearly constantly. Most if not all of Baldur's Gate 1's characters are very obvious stereotypes - the big buff guy who speaks with a gruff voice and likes to smash things, the cowardly effeminate wizard who "just wants to do research" and is scared of basic combat, the greedy shopkeeper who just LOVES ripping off his customers in obvious ways, etc. I don't really see how this could be particularly compelling to anyone - the world feels like a joke, like a parody of an actual DND world, and comes across as very badly written. I have heard BG2 handles the characters significantly better, but playing BG2 realistically requires playing BG1, which is a miserable experience to suffer through.
A lot of the minor characters in IWD can come across as a bit boring, especially the temple priests, barkeeps, and generally all the "utility" NPCs. But I find that the main characters, especially Arundel, come across much better than a lot of the characters in BG because they are written to have some nuance and are generally treated more seriously than a throwaway joke. IWD's main story is relatively simple and straightforward, and has very few sidequests, so I understand if people don't like that, but I find the actual worldbuilding is far superior to BG in every way, from the characters to the pallette and design of interiors to the ambient sounds, it all works well to create the atmosphere of a frozen landscape and trecherous dungeons. Most of BG's locations are just kind of generic forests or cities.
Probably the biggest problem with people trying to get into IWD is that the first part of the game (before reaching Kuldahar) is extremely boring. You're mostly fighting goblins in large numbers, and since you're low level, so it ends up being a frustrating experience where you will go into a fight and lose 3 members of your team due to random enemy ranged crits, then quickload and win the fight easily without losing any health because the dice rolled differently. BG technically has the same problem but it's less pronounced because you're generally fighting 2-3 low-level nearly worthless critters at the start of the game, so the odd hit on your characters doesn't mean as much. I consider this a flaw with the way DND 2e was designed, since at lower levels RNG has a much larger effect on the outcome of fights.
TL;DR Icewind Dale is good. The story to BG is okay but largely filled with extra filler and terrible characters, which really bring it down. Given that it's only real advantage over IWD is it's focus on story, I feel like IWD is far better overall because it absolutely nails what it set out to do, rather than being a meandering mess like BG. I'll take a very good dungeon-crawler over a mediocre RPG any day, especially given the way the gameplay in ADND 2e actually works and how heavily combat focused the mechanics are.
Baldur's Gate reminds me of those cringe "online DND campaign" series that people do on Twitch (Critical Role, etc), where everyone is always trying to be ultra-funny and do wacky things all the time to try and keep the stream interesting, rather than creating an intriguing world and characters. If you want a good story-driven game on the Infinity Engine, just play Planescape: Torment instead, since it's actually intellectual and isn't just Bioware-tier drivel dressed up as something far more profound than it actually is.
