Hundreds of hours spent on both
Morrowind and
Oblivion. All the expansions for both!
I love the Lore aspect of these games, plus the fact that you really
can play them the way you want. Also, unlike other so-called "RPG's" it is
entirely possible to screw your character up as you level them. Make some mindless decisions along the way and you'll get called out for it. Killed that Shopkeeper you wanted to buy stuff from? Tough. Levelled up by "cheesing" it and just made potion after potion? Now even the bloody WILDLIFE can kill you!
As I said I love the free aspect of it. All through
Morrowind I played as a Spell-flinging Uber-Alchemist, who had Potions and Enchanted items for every possible outcome. Then all through Oblivion I played as an ultra-sneaky Bow-equipped assassin that could quite literally one-shot humanoids from deep in the shadows. If they were lucky enough to survive then I'd instantly melt back into the darkness, leaving them all scratching their heads, wondering where I was. Until I removed it with the next arrow!
Spell-flinging Berserker in Full Plate armour? Possible.
Sneaky poison-coated dagger user? Possible.
Scroll-making Hunter with a speciality in summoning creatures to help you? Possible.
Idiot Bookworm Enchanter with full Mastery of cooking, but gets killed by anything larger than a rat? Entirely possible too!
Oh, and Skyrim's mine by default! But only after the first patch lands.
Freestyler: A customer that's too hard to please, complains all the time and wants everything for next to nothing.