I already have nwn2 and mask of the Betrayer i am curious about age of decadence tough also underrail sounds promising even if recently i am more in to dark fantasy.
You have to get Planescape Torment right now. I don't even like it, it isn't for me, but if you are into stories and lore and stuff, that is an essential play.
Personally my best RPG of all time is probably Betrayal At Krondor. Get that if you don't mind really old stuff. If you have a very high resolution screen, maybe just don't bother. But it is a great game.
I think Underrail is really bad, and there is a thread on codex that will explain most of the reasons why. Funny how so many people seem to like it now. I pity them greatly. Age of Dec I am undecided on. I got bored because it is like a pnp game which is all about choices and situations and stuff and I only really like RPGs for tactical magic combat, and AoD has none of that. So it depends what you like from RPGs.
Divine Divinity was a good suggestion. Not sure you will get much in the way of story and loregasm in that though, but it is a good clepto RPG with decent combat. Blackguards is basically a masterpiece imo. Also Drakensang was a good suggestion. Like a less dumb Dragon Age Origins. I completed the first game and got bored of the second game, yet the second one is probably better. I just lose motivation sometimes for questing and RPGs.
Maybe try Bastard Bonds if you want something a bit different and don't mind a simple indie game. The combat is super shit so again, I didn't play it for long. But the story seemed decent and usually I hate all stories. That reminds me, Witcher 3. Pretty crappy combat unless you can enjoy slashy slashy dudebro stuff, but the graphics are insane, it is like living inside an oil painting, and the characters and lore are good and it has some really good voice acting. Again, I play for combat and hate stories and dialogue so it wasn't a game for me, but I still really appreciated how well made it was.