the_atm: So If I were to get BG the complete saga from GOG, what mods should I install?
If it's your first time playing BG1, don't install *any* mods... none. A game like BG1 *needs* to be played raw to appreciate it in all it's ancient glory. Sure, the engine got an upgrade in BG2, but if you install BGT/TuTu for your first play-through, you won't truly appreciate Baldur's Gate at all.
Once you've played through at least once, that is the time to consider mods, but for BG1 mods are thin on the ground compared to BG2. I only have the Elven Charm and Sleep Racial Resistance fix component from BG1 Unfinished Business, for example, but in BGT in install BG1NPCs for a more interactive party.
As for other mods, it really is a matter of taste. Asking which mods you 'should' install of complete strangers is like asking which item of clothing you should buy -- everybody will tell you different. Get onto the popular modding sites and browse what they have, then decide for yourself.