Castle Kriegspire - best of the castles, not too big, not too small

The Hive - being ubers by the time you reach the end is classic MM. The Queen could have been harder, but that whole last room is way dialled up in the Merge Mod, you actually have to be strategic rather than just waltz in & blast away. Check it out

Best - disagree:
Tomb of VARN - interesting but ultimately too long for my taste, esp the Water Temple where you hang around for HOURS trying to clear the Genies

Best - my other choices:
Shadow Guild Hideout - I love this dungeon - almost my favourite with the Temple of Baa. If you didn't lose the Prince of Thieves, you might even miss it. Cutpurses are pretty lame for opponents, and the loot is meh, but it has more mechanical goodies: doors that open differently, and the floor tiles. And the ultimate reward is a four-way teleport room to some non-Town Portal maps, where you can plop a Lloyd's Beacon and suddenly your travel options have opened up hugely

Dragoons Caverns - surprise packet for such an early area. Bigger than first appears, hard-hitting enemies and the slime area where you have to use entirely different tactics

Temple of the Moon - small with a simple little puzzle but a tough final room protecting the Druid promo

Hall of the Fire Lord - something else you might miss with the only quest given inside. Like Corlagon's Estate below, you have to keep re-checking areas that open up as you explore

Temple of Tsantsa - just cool. Like Corlagon & Fire Lord, you have to keep re-checking areas that open up as you find the levers. And that final room with all the Cobras is wild for a lowish-level party

Supreme Temple of Baa - decent size, need to keep your wits about you, some secret areas to discover, and I'm a sucker for anything with mechanical elements

Worst - agree:
Free Haven Sewers - good idea, and not badly set out, but the enemies & loot are underwhelming. However, you could even argue this is on brand, with of course rats being the main things in sewers. Could have been beefed up as a Prince of Thieves hideout with some henchmen & lair loot - they improved this in MM7

Worst - disagree:
Goblinwatch. I love Goblinwatch. Not sure why, I just always have. As above, the cheesy mechanical puzzle, it's bigger than it first appears but not too big, and the hidden chainmail in the wall is a good early-game easter egg

Corlagon's Estate - I don't hate this at all. Decent puzzles where you have to keep re-checking areas that open up as you find the levers. It's not a favourite, but not on my least favourite list

Silver Helm Outpost - this will be a recurring theme: not a favourite, but doesn't deserve a least favourite. Fine for what it is

Gharik's Forge - as above. Not a favourite, not terrible. Insanity hardly matters, and again I love any kind of mechanical puzzle (the bridges)

Castle Darkmoor - yes it's large, annoying and confusing, but that's kind of the point. By then you're almost walking around smacking stuff with no concerns; this forces you to reassess. No buffs, no Wizard Eye, mapping largely useless.....welcome back to reality, my previously smug party. Not a favourite - probably not anyone's favourite - but I like that it exists, if only because The Hive is somewhat of an anticlimax. Oh and BTW, in the Merge Mod, Eyes are now immune to Dragon Breath. You think you hate it now!

Worst - my other choices:
Caves of the Dragon Riders - my god do I hate this. No quest attached, just caves and caves and caves of Dragons for those who have to complete everything. Ugh. I hate this so much

In Darkmoor, Dragon Breath will very swiftly dispose of the Eyes, and nothing else will survive Shrapmetal at contact range. Just blast away and then beacon out, recharge from the Fountain of Magic, and beacon back. Rinse, and repeat.

The two dungeons that I've never particularly liked are Varn and the Hall of the Fire Lord, both of them because they are big and complicated, and in the case of the Hall of the Fire Lord, you have to go over the same ground again and again to make sure you haven't missed something.

Similarly, I always do the "octagon room" in the Shadow Guild, but I try never to do it more than once. I've always thought it a bit of pain to have to go trogging slowly and carefully around the floor to trigger the teleport to just outside the "4-teleporter room". I never go back there unless I lose the King of Thieves after I've captured him and before I've delivered him to Anthony Stone.

I really like the Hive too. Just as you said: it has great atmosphere. I don't care if it's too easy: I think that it's actually kind of the point.

What I love about MM6 in general is how it has several stages, each feeling almost like a different game. At first, you don't even feel like a hero, and a couple of bats and rats is more than enough for you; here you have to be cautious and pick your battles. Then you get into the "early middle game" that I enjoy the most: you have some nice items and start to get useful spells, but you're far from "maxed up". You have an immense freedom to go anywhere and do anything, you start working some of the Council quests and promotions. Then you obtain Fly and Town Portal/Lloyd's Beacon spells and the game suddenly plays very differently (you need to go more linear as well). And in the last stage, you get blasters and the game plays like a FPS. I consider the Hive to be a sort of a "reward" for the player: you've fought hard to get the blasters, now you can enjoy blasting through the Kreegans and finish the game. I also like it doesn't overstay its welcome.

Tomb of VARN — agree completely. Somehow, I just like how huge the MM6's dungeons are, and I like that navigating around them is an actual challenge. The sci-fi elements like the radiation and the Star Trek room are very nice too.

My only problem with it is that the developers have restricted themselves to 3 monster types per dungeon. And because there is a single robot down in the control room, you have only 2 types for the rest of the huge dungeon. I would like to have more.

Castle Alamos — nobody has mentioned it yet, but I like it too, for similar reasons. The dungeon is huge, with different interesting parts, and you can enjoy some good combat and good loot there.

Silver Helm Outpost — here I disagree completely. I enjoy this dungeon quite a lot. Not because of its construction, but because it forms a kind of "rite of passage". Defeating the captain and the monks is difficult, but it feels good. And since there's only one captain and not so many monks etc., it's doable and, for me, enjoyable. However, I agree with the stairs being clunky and a bit frustrating.

Goblinwatch — it's interesting you classify it as one of the worst. I would say it's one of the best, and a very good first dungeon. It's not small, but not too large either, it has various nice puzzles and several different parts where you have to employ different tactics. I also think it has a great atmosphere (actually, when I played MM6 as a kid, the various growling sounds scared me so much that I didn't go in that dungeon at all!) And the goblin guard on the top is priceless (you can talk with him about humans, and he explains how pitiful they are ). But I can agree that the Abandoned Temple is not that great, though I don't think it's too bad, too.

Sewers — I liked them for some reason. Probably because there are so many entry points through various houses in the city. The fact that the loot is worthless and the enemies weak didn't bother me, really...

However, the Halls of the Fire Lord don't belong to my favorites. I find them to be more confusing than VARN, less atmospheric, they also have only two types of boring monsters (because there's one jackal man somewhere), and it doesn't have any kind of "rewarding conclusion". To top it off, when I went through them, I didn't get a key from the jackal man due to a glitch, and I had to hack it in using a save game editor.

Darkmoor — I must agree with Ossie: of course I suffer when going through, but it forces you to play differently, and that's a good thing. It adds to my rejoicing about how the game shifts gears many times, feeling very different each time. And the cathedral buried in a cave beneath the castle is IMHO very nice.

Agar's Lab -­ I'm surprised anyone likes it . It's not good for anything, and for me, it's just a generic dungeon with uninspired layout, lots of those cursed eyes, and very slim loot .