Where's the best place to find a real live adult male (not a large child)

I’ve been in a relationship for the past 10 months with someone who is not interested in (or probably capable of) maturing. The way we broke up illustrates the depths of childishness he’s capable of. I feel like I’ve been wasting my time and am not interested in a new relationship that is with someone immature and with someone who isn’t interested in moving on with their life in the same way that I am.

I have recently joined several online dating sites since its hard to find any single guys in my area and I have no interest in what can generally be found in the local bars (old creepy guys who just want to talk to your boobs and rednecks).

Are there any sites that anyone has had any luck with or would recommend? Any places where you’d recommend looking for a real, live adult looking for a long term relationship? Its a small town without many options (a couple of bigger towns around) and I’m a busy girl.