The other extreme, could be games where you are stuck with same loot forever.

Like Risen or the Gothic games.

Essentially you have the same armour forever.
Same weapon forever.
Same shield forever.

Perhaps there is so few loot, that is like no loot at all.

BOTW was pretty fun. The exploration and side quests were better than anything the main quest threw at you. With the exception of the Guron quest because the dude was voiced by Keroro from Keroro Gunsou which made it an enjoyable escort quest.

Lords of Xulmia looks to use a map system where you select locations to go to. I'm wanting more exploration.

I played a lot of the retro recommendations as a kid. They're pretty good games. Everyone needs a chocobot.

I started playing Fable and Kingdom of Amalur. I liked both but neither gripped me. Fable feels a bit too rail roady in how little you have to explore, it's too many narrow paths with arena sized areas every so often to spawn enemies in. Reminds me of a PSP game where they limit hardware problems the same way. Amalur is brilliant and almost exactly what I want but it has the opposite problem. Because it's an ex-MMO it feels really empty and barren more often than not. if I could get Amalur's mechanics in a better world layout I would be in heaven.

Thank you for the suggestions everyone.

How about rogue-likes?
-Moonlighter
You collect loot to sell or create new items to small backpack, some may be the same, but they have different condition to keep them in your bag.

-Endless of the Dungeon
Mix of tower defense and tactical rpg. Each time you get different items which can give us new skills.

-Slay the spire
Cards rpg, in which each your action is represented by card. Your loot are card adding new skills, different potions which can be use only once and artefacts which can contain blessings and curses.

Dwarf Fortress. (Adventure Mode)

It has all you're looking for. Open world, loot matters, and you can even become a bandit or something.

I think you tried Witcher 3.

I absolutely hated it. The horse controlled it's self, the combat was 1 button counterfests and then I got a bunch of dialog wheels. It was pretty much everything I hate in modern gaming wrapped up in an extremely pretty package. It's one of the main reasons I made a forum thread. Every thing you search is full of the same 20 or so games with Witcher 3 at the top.

Spire looks good. How Early access is it?

Two Worlds, at least the first one, is like the opposite of what OP is looking for, in my opinion. The mechanic that allows you to combine identical items to get a slightly better one trivialises the entire loot system.

That's a tad harsh. The game may be getting a bit old, but the upgrading system is quite innovative. When you
combine the 2 swords the value increases as well.

Besides, have always liked this game:)

Slay the spire has 3 fully playable characters, each with different class/playing style. Well, they could get out from early access at any moment, but probably after 4th character.

It is true that open-world today is, often, translated with "huge/long", but not necessary "open".

The games I'm trying to suggest are all old-timer, really old, like Ultima 6,7 or Darklands.

Today everything is done to please the player, often envisioned as spoiled kid, that needs everything now.
New weapons every 5 minutes. New armours. New spells. New something else.
Of course, with this is mind, items tends to resemble one another.

Realistically each weapons is quite different in it's usage and effects. But games are quite simplistic: swing the <put your weapon here> doi some <put damage here>.

Yes, it was a very original system and initially I thought that it's a cool idea. But over time I came to the conclusion that it's utterly dumb. I mean, consider this: common armor is potentially more powerful than rare armor because you will probably find enough pieces of it to upgrade its parameters beyond the better item. It's not only absurd on content-level, it basically breaks the loot system.

I always tried to like this game. Really hard. But the more I played it, the more I grew convinced that it's pretty bad.

I haven't tried Elex yet, but I saw it had some very different weapon groups. Has anyone here tried it yet?

I was referring to a particular genre: RPG open worlds.

I quite suspect that shoot'em up will provide upgrades quite fast.
You don't want to to get stuck with same fire mode for 1 hour, if the entire game length is two hours.

It is also true, that older RPGs, where so much more unforgiving that today; but yet in a fun way.
Dark Souls is just annoying for the most part, as oblige you repeat the same sequence over-and-over again.