Legend of Grimrock II is fine, arguably better than the first game and certainly bigger in scope. I just enjoy the first a bit more, personally.

I would say The Dark Spire and the Etrian Odyssey series (all on the Nintendo DS).

How about Elminage Gothic? I should warn you, however, that the game is rather brutal after the first dungeon. (One tip: If you just want to beat the main story, you never need to pick any locked doors; the areas behind them are all optional. Another tip: The enemies on the last level of an optional dungeon tend to be very dangerous, so you might want to try going somewhere else if you run into that situation.)

One obscure dungeon crawler that I happen to like despite serious issues is Centauri Alliance, which can be described as Bard's Tale in space. It has some interesting mechanics (transformations, technical skills, level up skills with XP rather than getting global levels), though it did have some serious issues (major bugs (one of which allows for a major exploit, but hurts normal gameplay), clunky interface). From a modern standpoint, however, the biggest problem was that this old computer game had no DOS version; it was only released for the Apple 2 and Commodore 64.

Personally, I prefer the way Dungeon Master handled certain things, like the growth system and potion creation.

That's great. I've never played a Dungeon Master title, so I went with what I have played and enjoyed.

(Though as I think on it, that may not be entirely true as I have vague memory of playing an Eye of the Beholder game extremely briefly - not enough to formulate any opinion of it though)

I love that one, superbly fun game. And that's not nostalgia talking - I only played it for the first time when I bought it here. Still, it's not exactly a dungeon crawler, I mean there are dungeons in it, pretty elaborate ones, but there's a pretty big world to explore... even if the outdoors are corridors too.

Personally, I think I'd say the first Diablo. There's just something so pure and straight to the point about that game and its dungeon crawling nature. It's just you, and those huge, spooky, gothic catacombs full of monsters, traps and death. Almost no plot, but enough lore to give things some weight. Not to much shit to worry about leveling up. Nothing weighs it down. The atmosphere is perfect. I mostly love the first half of it, when we're still recogniseably in the cathedrals catacombs. When it goes all lava flows and hellscapes it loses that unsettling feeling.

I also liked both Legends of Grimrock, even if the second one actually slightly disappointed me. I think it got a bit too big for its own good.

Diablo, Revenant, Demise, Dungeon Siege, and Pool of Radiance(Ruins of Myth Drannor).

The thing is:
* I like Dungeon Master because of its less common systems, like getting XP in different classes based off your actions (and you multi-class just by performing actions that give the XP to a different class), and using spells to create potions from empty flasks. There's also the whole magic system, allowing you to cast any spell in any of 6 power levels, and allowing you to discover spells by experimentation (or even by accident, which has probably caused some parties to be torched by unexpected fireballs).
* Eye of the Beholder, on the other hand, copies D&D mechanics; from what I understand, XP is only gained from killing enemies (unless there are scripted XP rewards, like the ones Dungeon Hack gives you on reaching a new dungeon level IIRC), which is a rather dull mechanic. Also, potions would only be single-use items that you find and aren't re-usable, and magic follows the clunky D&D system. Hence, the game just does not seem as interesting to me. (There's also the problem that D&D mechanics are terrible at really low levels (too much missing and attacks that do hit are too deadly), and they don't scale at all to higher levels (there's the example I've given where, in 3.x (with Epic Level Handbook rules), a 1% difference in level can mean the difference between 5% and 95% hit chance once you're around level 2000).

Just be aware that Pool of Radiance(Ruins of Myth Drannor) has a critical bug that can cause serious data loss if you try to uninstall it, in at least one version.

Watched some videos on Lands of Lore: The Throne of Chaos. Love the art style and the voice acting!

Off the top of my head (and my desktop): Daggerfall, Dungeon Crawl: Stone Soup, Din's Curse, DoomRL, Barony, Castle of the Winds. I'd also say System Shock should just about count, since it's pretty much "cyberpunk Ultima Underworld on a space station", but without an RPG-style progression system.
Honorable mention for Spelunky, too (more of a "dungeon run-and-jump-er" without any RPG elements, but it takes place entirely in a dungeon :P ).

Eye of the Beholder, Ravenloft series, Might and Magic 6,7,8.. Angband.

Wizardry 8 for Western type dungeon crawlers is still my all time favourite. From what I've tried of Grimoire so far that could well match it.

For the Japanese side of things, nothing compares to the Atlus RPG's, mainly the Shin Megami Tensei series and all of its many spinoffs- especially Persona of course.

When I think dungeon crawler I think blobber, and my favorite is Lands of Lore. It's one of the first RPGs I played on PC actually, and I still love it. I don't think it's all nostalgia either, it's a great game.

Dungeon master for the reasons dtgreene gave + fond memory of how I litteraly felt from my chain the 1st time I hit level 12 and was given a "warm welcome" I didn't see coming while turning in a corner. That was more than 30 years ago...

Ultima underworld, but it's messier than Dungeon Master.

Mordor: The Depths of Dejenol is one of those unfortunate Windows 3.x games that won't run on most systems today due to the circumstances of the program; especially seeing as the fandom for the game basically died out in the WinXP era.

Hello,
for me it would be difficult to name only one. There are multiple, which I favor for different reasons:
My most played (favorite) dungeon crawler would be either Brian Fargo's "Swords & Serpents" on the NES console or "Icewind Dale" on the PC.

But I am also very fond of "Die Schicksalsklinge" the first part of the "Nordlandtrilogie" (also known as "Realms of Arcania: Blade of Destiny") on MS-DOS and its predecessor "Spirit of Adventure" which is more similar to the Bard's Tale series. But the former is also an in-depth travel or trekking simulator, and the latter is remarkable for its naming of streets in its huge capital city.

Other not so common recommendations of mine would be "Amberstar" on MS-DOS or some unusual ASCII roguelikes, such as "SIL" with interesting stealth mechanic based on awareness, or the 7-day-roguelike "Vicious Orcs" with spatially different dungeon layouts, more explicit world representation in its use of colored ASCII symbols and very interesting two game endings.

Considering the usual suspects of strictly first-person blobber-style dungeon crawlers, I would rate the following quite high, as well:
- Dungeon Master (for its great and somewhat plausible room layouts - I never felt the need for maps.)
- Might and Magic III: Isles of Terra (for a fantastic sense of exploration in its quite open and colorful overworld)
- Lands of Lore: Throne of Chaos (for its gameplay accessibility combined with beautiful 2D graphics despite its late game spike in difficulty)

[Edit:]
Regarding the two "Legend of Grimrock" games, I do prefer the first one. Its more puristic approach and single dungeon felt more atmospheric to me. The second game is missing something to smooth out the transitions from one environment to the other - the island almost appears like a theme park. Both Lands of Lore: Throne of Chaos as well as Might and Magic III: Isles of Terra did it better with the inclusion of scenery still images before entering a different environment! Furthermore, I did not like the huge enemy mobs, especially not in the boss fights, of Legend of Grimrock II.
[End of edit.]

Kind regards,
foxgog