Dishonored or Oblivion

Definitely Dishonoured. A fairly personal opinion, but I'd say Oblivion is the weakest of the modern Elder Scrolls games.

Go with Dishonored.No doubt Oblivion is very fun,just i dont think you can fully enjoy it after playing Skyrim.

Dishonored.

Oblivion. Dishonored is one of those play it once and done (one and done) kind of games.

Oblivion

I would go with Dishonored.

Oblivion. One of the best games I've ever played (Haven't completed it though).

I like dishonored.. but not as much as i thought I would.

Oblivion is a open world game, you do what you want and go wherever you like. Dishonored is a linear game, you have a mission and you need do it, but the game give u many ways to make it.
look for some gameplays on youtube and see which you like.

Between those I would choose Oblivion. I spent hours and hours playing it on console and had loads of fun. Dishonored is good but it's short and doesn't give you much many hours.

Oblivion

Black Flag

Got dishonored. Thanks everyone.

If I were to choose, I would say Oblivion, because I had a ton of fun with in on Xbox 360, and now I'm replaying it on PC. And the mods add extra value ^_^
As for Dishonored, I got bored and stopped playing it half way... (:P). After months I still have it installed, so that means I will continue at some point, but not now.

IMHO, a lot of you are missing something important.

Oblivion, is the better game and loads more content. And if you have a very limited budget and want to maximise hours/dollar of course go there.
But, considering you played Skyrim first, you will likely find Oblivion outdated and clunky. Skyrim did a lot to provide really interesting, unique, and fun places to play. Oblivion, even with mods as far as I have seen is somewhat bland similar dungeon after dungeon. And the combat is so much more clunky. I would never go back to Oblivion now after having played Skyrim, there is so much content in Skyrim and new mods to explore I would just play more Skyrim.

So in general, I recommend Dishonoured. And unless you have completely tapped out the enjoyment in Skyrim, and want to absolutely maximise yours hours per dollar, I think that is your best bet.