If it's your first playthrough, don't use any mods. Not just for "purity" sake, but for the sake of your own sanity.
They are all in quality far, far below the original. Except maybe "Ascension" mod by Gaider himself, but that's not fit for first playthrough either.
The mods that introduce new NPCs and lots overpowered items and spells, yes.
But BG1 NPC Project, Sword Coast Stratagems and the various fixpacks mods are quality mods.
You're probably right in BG1 department - I've only done vanillla BG2 + ToB playthroughs (and never encountered any bugs or problems there, so need need for fixpacks etc).
I'm pretty clueless when it comes to BG1.
BG2 doesn't really need any mods, except perhaps the Fixpack. Unfinished Business and SCS is nice too. And Ascension, I guess (I never completed ToB).
BG1 OTOH really needs mods like BG1 NPC Project and SCS to be more than a mediocre game, IMO.
And either EasyTuTu or BGT combined with a widescreen mod. Playing in 640x480 resolution on a 22' monitor is just too claustrophobic...