It depends. If you don't mind that Hitman has changed the formula a little bit, trying to take the game to the next level, this game is fantastic. I have been playing non-stop and enjoy it. I also have so many hours into the previous games that I am sure that is a large part of why my grades failed at the time.
Dishonored is a great stealth game and all, but it really was a disappointment overall for me. I have fun playing it, but I feel like there is too many annoyances and obstacles, where it went from stealth to just zip around until you get to your target.
Either way, Hitman is more of an action stealth type of game, whereas Dishonored is more of true stealth game in a manner of speaking, as it encourages you to almost never be violent, but ultimately you can shape your ending...for what it's worth there. Hitman would be my go to game simply for the Contracts. I always wanted more levels to play and I know some people are going to figure out truly challenging things to complete. That will keep this game fresh for me for a long time, where Dishonored has already taken a beat seat.
Currently playing: FFXIII-2, Uncharted 3, WWE 12, and soon Darkness 2 PSN: AdventSteel