Pandora Hearts, Makai Ouji: Devils and Realist Recommendations
Not too much similar plot-wise but it has that slightly gothic atmosphere to it, both main characters are royalty and also have rather similar personalities. Plus, within the story there is a talk of contracts and the ability to summon demons. If you do like Pandora Hearts I can assure that you willl enjoy Makai Ouji - Devils and Realist too.
Very similar in characters, but yet to early to say the story is similar.
But so far I guess if you liked one of them, you will like the other^^