ok, so, do you think i may have any chance if i brought 5 other guys with me? would that still be funny?
I'm sorry, I wasn't trying to be sarcastic.
In reality these dungeons will test the highest level characters with even the best equipment mods will supply you with.
There's no easiest one.
For a stealth class high chameleon and marksman with a heap load of poison potions made with the highest level of alchemy you can obtain.
M?l?e? Wow, that one is absurdly difficult. I eventually conquered them using the swords from Adonnays Classical Weapons mod. The damage dealt by Reign Of Truth and Trust are non reflectable to your avatar, but even so it took me six or seven efforts to do Ancient Goblin City.
I honestly went though over 250 homemade restore health, magicka and fatigue potions getting through to the boss, and then promptly died four times from that save game before taking him down. (see this thread for the gory details)
http://www.gamesas.com/bgsforums/index.php?showtopic=720096&hl=grash
If going with a magic class I'd deem these as impossible.
If you do manage to survive and complete them with a lower level character even with companions in tow, it would in my opinion be quite the achievement.
Good luck with it anyway.