1. Vanilla
BG1: old, clumsy, low resolution, game limitations (low stacking, pause while on map/no pause while in inventory, slow AI). While it still keep its charm for me, who first played it in 1999, this charm would be wasted on a new player. I could try to fix vanilla manually, but IIRC widescreen mod don't support vanilla, and I’m not sure whether BG2Fixpack supports it as well. If it doesn’t, then I had to revert to Dudleyfix, which I haven’t used for ages and not sure I’m still fluent with.
All of the rest options, each letting to play BG1 in a newer engine, share the same issue I'm concerned with: vanilla BG1 got about 6 weapon proficiencies and certain number of skill points to put into these proficiencies. BG2 engine boosts number of proficiencies about 3 times, while number of skill points remain the same, which effectively means that average character by the end of any of "BG1 in BG2 engine" implementation will be proficient in 3 time lesser number of weapons, give or take, compared to vanilla character. I played TuTu/BGT for so long that I take it for normal, but I figure it would ruin correct game impression for a new player. Other than that, each option had it's quirks.
2. TuTu: I used to like it years back, but as of now it haven’t been supported in what, 6 years? Not sure if it is capable of providing coherent, easy performance for a new player.
3. BGT: better than TuTu in that it’s still (to an extent) supported, but still my concern about weapon proficiencies remain.
4. BG1EE: I never cared to give it a honest study before, so I know little about it. However, seeing as how I’m picking an option for another player, not for me, I figured I should conduct some research to see if it might be viable option for a BG newcomer. To sum my study, among its downsides are only partial implementation of TobEX, ingame videos replaced with a horrible mockery, and I also stumbled upon quite a few of statements that there’s some parts of game content actually cut from EE compared to vanilla. Sadly, I’ve never found any details on what exactly these missed parts were, though. The upside is that they added a number of bonus weapons, which should alleviate somehow the issue with weapon proficiencies.