At least with Sterling, you get to have more fun. Roger doesn't take himself so seriously. He's more of a roll with the punches kind of guy. He actually cracks jokes and smiles every once in awhile. Sure, he'll probably get you pregnant and blow you off by never calling again, but at least he'll have taken you out for a night of martinis and dancing. He'll even drop acid with you, while Don's sitting around having hallucinations that aren't even drug-induced.
And while he's got a lot of baggage of his own, at least his crazy daughter is grown up and the rest of his children are illegitimate. Don's got three young kids you'd have to help raise. Chances are, you'll probably have to take Sally to the abortion clinic one of these days and Betty will probably murder you when she finds out.
The other good thing about Sterling? He doesn't take his career quite as seriously as Don. He likes to put in a face, yell at a few people, take a nap in his office, and then wouldn't think twice about taking a half day so he can meet you in a hotel room across town.
Both guys will definitely break your heart and fuck you over, but at least with Sterling you'll have more laughs in the process. Plus, how many guys can rock a grey mustache?