3E: Vault of Larin Karr, The Grey Citadel, The Spear of Loghin, Freeport series
Non-3E: Festival of the Damned (Ars Magica), Complete Masks of Nyarthalotep (CoC), Beyond the Mountains of Madness (CoC), the Enemy Within Campaign (Warhammer FRP)
Of all those, Festival of the Damned has impressed me the most of any adventure out there. It has it all, in-depth roleplaying, investigation, combat, extremely detailed subplots and NPCs, and moral dilemmas. If you haven't checked it out, I'd recommend it. Its also pretty easy to convert over the 3E.