At the moment I'm just cheesing and yeeting in heinously vanilla with maybe a few visual mods that work without the unofficial patch, like Leanwolf's Better Shaped Weapons. I've never had a non-pirated copy but if you do, try Requiem, or one of those massive mod packages that include it like Lorerim.
Off the top of my head, to bring Skyrim even up to Oblivion mechanic:
>Nemisis behaviour engine
>Combat Behaviour Improved
>Combat Gameplay overhall
>Disparity was my fav race mod but almost any will be a vast improvement
>Daedra by weirdrussiannameguy for some breddy high quality scamps and daedroth added to the world
>Mysticism for all the missing spells
>some like Summermyst/Wintermyst for more enchantment types
>Morrowloot (MLU seems down smh) to make loot rarer/encourage exploring
>Revenge of the Enemies handled some of the things MLU did plus made vampires more spoopy
JKs Skyrim for better looking cities
>Immersive sounds Compendium was breddy good apart from the out of place low quality bear noises
>SMIM and RLO for nicer interiors
And Sophia was the only cringe waifu mod I used, 6/10 still miles better than Serana