I've started Arcanum five times and never finished (probably never will) it gets boring really fast for me. I don't know why. (I'm playing right now, by the way)

I would recommend:

Neverwinter Nights
Knights of the Old Republic
Dragon Age
Mass Effect

Yeah... all of them from Bioware. ;)

Might and Magic series (I have enjoyed VI and VII so far, will probably do IV/V next)
STALKER series
Star Wars: Knights of the Old Republic
Ultima Underworld 1+2
Vampire the Masquerade: Bloodlines

I know what you mean. Neverwinter can't hold a candle to BG but I like it all the same. Hordes of the Underdark is the best of them (Hordes > OC > Shadows (Shadows is too short for me))

I just don't get your hate towards Forgotten Realms. :(
I mean, it's not Middle Earth, that's for certain, but I love the setting even so.

The problem that I have with Forgotten Realms is that it just feels so incoherent. It tries to cram every single fantasy staple, and then some, into a single world, and it just becomes too much. They should have downscaled things a little bit, and instead of focus on quantity of stuff, added some fresh new touches and developed what is there a bit more. Many fantasy settings does the same thing (Chronopia probably being the biggest offender here, as it tried to fit most fantasy staples into a single city. Yes, there are dragons in it, and yes there is an elven forest in it as well!). But as it stands, Forgotten Realms just feels like someone tried to fit everything they knew and liked about fantasy into a single world, and then tried to make things work, rather than the other way around.

You know... You might be right. I never actually read any FR books or anything. I just played games based on this setting.
However, all the games I've played (with a few exceptions) are very good.

'
I feel that the computer games in many ways does a better job of making the setting interesting than TSR/Wizard's of the coast every managed to. Still, I wish someone of TSR's other settings would have become the main one, they created a few rather interesting ones (and some that were just bizarre, like Spelljammer. There were actually such a thing as a miniature giant space hamster in that setting)

Man... I would pay good money for another game with Minsc and Boo in it. Seriously...

Same here. I would love to see the old Bioware guys team up and make a proper Baldur's Gate 3, or just something set during roughly the same time period, so they could have old fan favourites show up.

Too many RPGs here! Let's infuse this thread with some FPS manliness! I recommend the STALKER series. Unreal, as well.

Well... STALKER doesn't really have that interesting universe and background, neither does Unreal. Both System Shocks, however, or The Shooter Which Name Is Eluding Me...

Well that's a good point. They are very immersive and well-realized... but the backstories of both are pretty thin.

Most immersive apart from the ones you already played:

The Gothic series (1+2, witch fanpatches also 3). There is no 4th part!
It has a living world wheere poeple actually follow their daily business routine, a world that is in fact dangerous (beware of those boars!) and great, well fleshed ou characters that reappear thoughout the series.

Then of course there is Mass Effect. Really good games but if you don't like DRM, keep your hands off!

Not an RPG, but for having a great atmosphere that really takes you away is Bioshock (the first one mainly) IMO. Just check out the introduction on youtube.

Oh, and of course Stalker: Shadows of Chernobyl. Also very very atmospheric and although being a shooter mainly it as RPG elements. In fact, in terms of immersion I guess this seconds the Gothic series in my book.

I won't lose a word about the Bethesda games (TES series and Fallout 3) since I guess you know about that already :).

Edit:
Can't believe I did not mention GTA. Again, I think you may already know those, but definitely worth mentioning :).

As for the RPG section, Vampire the Masquerade: Bloodlines has a cool story line too, but the world is a bit limited.

How about Pathologic, if you need some FPP? :)

Games also deserving some mention in my humble opinion include both Witcher games, and Sacrifice. While the world of Sacrifice can't be called too deep and complex, there's something profoundly mesmerising about it that made me feel very attached to it. Which is a major plus for a game concerned with world-changing magical events/cataclisms!