This post will cover the best mods for Dragon Age Origins. They are an important aspect in almost any game. Why would you use them?

They fix multiple bugs that may be left by developers
They enrich the game world with minor environment changes
They add a breath of fresh air to the game if you played it multiple times
It adds quality of life improvements, where you can save lots of time

Dragon Age Origins Vanilla mods

Here I would like give a list of DAO mods that do not break the vanilla experience, but rather improve it by a large margin

Lock Bash - I was a bit in doubt whether this mod should be used. But after seeing that there is a chance that the items may be lost, it provided optimal risk/reward for me.
Forced Deathblows - This mod adds some spice to the combat by often providing death kills. I use the Lieutenant file.
FTG Quickbar - I am playing on an Ultrawide QHD screen, so it is good to have use for that big screen space.
FTG UI Mod - same as above, the character and skill screens were hard to read. This mode gave a decent improvement.
Dragon Age Rules Fixpack - I removed most of the tweaks because I thought they would impact the vanilla game too much.
Qwinn's Ultimate DAO Fixpack - mod with a huge list of fixes, I could say it is something similar to Skyrim Unofficial patch.
DLC in Awakening and Awakening Fixes - More fixes. It also allows moving some of Dragon Age Origins DLCs to Awakening expansion.
Theta HD - some textures, to create some new looks.
White Teeth - this mod fixes a particular problem. That is bloody teeth after fights. This looks unnatural and for some people irritating. I definitely recommend trying it out.
Improved Atmosphere - This one is tricky, I followed the manual to install only those parts which add new animations, companion dialog changes, scripts, and conversation improvements.
Auto Loot - I think this is a very great quality of life mod. It saves lots of time and picks loot automatically. However, be careful with it on your first playthrough as it may confuse you a lot when collecting quest items.
4 GB patch - this mod allows increasing the maximum amount of ram that the game can use. This will make the game much more stable

Dragon Age origins - other mods

Universal Dye Kit - allows to dye armor colors. This is a perfect mod to bring fresh air to the old armors that you may have seen many times.
Skip the Fade - this is an amazing mod. Personally, I do not enjoy this part of the game. Thanks to this mod you skip the tedious part of the game. Moreover, you get all the attribute points.
Madd Gift Guide - I recommend this mod for a second playthrough. This highlights for which companion the gift is intended. When playing the first time it is fun to test and guess the perfect fit.
No Helmet Hack - this mod is for those that would like to see the Grey Warden's hair instead of a helmet.
Alley of Murders - give this one a shot. It gives some new side quest content. To start the mod you need to enter Denerim Market District or reenter it if you are already there

I would like to hear what is your suggested modlist for DAO, or what I could add to improve the game