Joker: He would have to be my number one choice simply because I admire his overall badassery (In the Dark Night at least) , his way of eliciting laughter from me as I partake in horrible situations... and his spiffy suit
Two face: I would gaga every time I saw the left side of his body, Which would most likely get me a 45. round to the dome. (Without a coin toss)
Riddler: I agree, you probably have the longest life expectancy with Riddler, but in my opinion he is probably the craziest of the lot, since he uses human life just to prove his intellect.
Scarecrow: I think I will pass, simply because of the off chance of me catching A whiff of his "your worst fear inducing gas" unless I had a gas mask, Then I would hesitantly oblige.
Mr. Freeze: Unrelenting ice, freeze, and Christmas references? No thank you.
Poison Ivy: She gives me a PETA vibe
Penguin: He is not so much as crazy, as just a enigmatic business man, which would probably pay well but would be relatively boring.
Ra's Al Ghul: He has an extremely attractive daughter, A great ninja training program

and 100's of years worth of experience. Except he wants to destroy most of humanity... Well... Shit
Your amazing if you got my horrible "gaga" joke <3