You are basically talking about Bug Fixes, Textures and User Interfaces.
Quinn's - it's a staple for storyline bug fixes.
Dain's Fixes - only use _Core, Bug Fixes and Cosmetic. The other two folders are meant for subsequent play throughs if you want to experience the base game.
Happy Owen Sells Far Song. This is controversial, but if you plan on playing with a bow you can completely miss out on this bow if you make the wrong choice in game in regards to the Redcliffe questline. Lets just say the choice you need to make and the way you get it in game makes literally no sense. Don't load this if you want to see how jacked up they made that quest.
Textures: Won't dive into that, too much is based on personal preference.
I'll list one:
Bow Replacer. You'll understand why you'd want this if you play with bows and see how they look in the base game.
FtG UI Mod, it's a staple in my load order.
Dragon Age BIK Improvement Konversion (DABIK) - it upscales the cutscenes - check the hardware requirements.
Others I consider viable (but completely optional) for a 1st play through:
a) Extended Dog Talents - if you want to roll with the Dog, he takes up a companion slot - so this helps balance him somewhat (he's underpowered compared to regular companions in the stock game).
b) Madd's Gift Guide - gives better documentation on the gifts for companions in the game - mainly who they are meant to be given to. In the base game you are left with simple trial and error - which after a while becomes tedious.
c) Two Spec Sten. Sten is the only companion in the game that only has one Specialization slot, this fixes that so he's more customizable.