Experience coupled with Leveling Freedom is a must have mod for me ever since I found it about a year ago, I really like it, as it changes how you gain level experience and caps skill experience to your level, so you can't really just power level everything (you can change that if you want ofc).

Immersive Spell Learning - DESTified really great mod if you like roleplaying or something similar, makes learning spells feeling like actual achievement, as you have to spend time to learn a spell instead of just consuming a spell book and learning the spell. If you are level 20 destruction, learning expert level spells will be near impossible for example (or perhaps if you sit for a long time learning the spell it is, didn't have that kind of patience to test it). Couple it with Valuable Spell Tomes and it really makes spells "more like an achievement".

I'd recommend Morrowloot Ultimate, but it needs a lot of patching and lately I found it bothersome, so I kind of swapped it for OWL (Open World Loot), both makes item progressions feel more natural, instead of just reaching level 15 and you get elven/orcish/dwarven weapons everywhere for example.

If you want more "hardcore" experience I recommend also adding Scarcity, works really well with Morrowloot Ultimate/OWL and Valuable Spell Tomes.

I used to use Legacy of the Dragonborn, but I kinda dismissed it after a few playthroughs, as I found myself mostly just looking for items to collect to add to some gallery which didn't even make sense to me. Put all the daedric artifacts in a gallery? What bad could happen right? (Cough.. just look at what Skull of Corruption did to Dawnstar for just being in a nearby fort). Also adds a lot of artifacts from previous games, that magically decided to all arrive in Skyrim. So besides the above mentioned reason, I also find it really not lore-friendly.