Dark Messiah is cool to play, especially with a staff. Many OMG SWEET moments.
Morrowind isn't much of an action game, but it's about freedom of play, LOTS of quests way better than in Oblivion and much better story. Until now there are shitloads of mods to it, which make the game even better. Morrowind is one of my favorite games in fact, I had high hopes that Oblivion would be, too. The result of those hopes is pretty obvious, I think. Wasted time and money. (the worst thing in Oblivion is that it takes some time to realise the game sucks horribly, you want to think that soon something interesting *has to happen*)
Gothic 3 isn't worth the time or money you'd have to spend on it, even though the story is better than in Oblivion. Story? Nothing particulary fascinating and gameplay is unbalanced and boring (usually it's you vs 100 orcs tossing auto-aimed fireballs on you). Not that is completly bad...it's just not good enough, for me at least.
Didn't played the rest.