You're probably get a bunch of different answers on this topic. Ultimately it depends on what your final goal at D1 is. If you want to try and build a low level team into a contender then you could take on a D- or D job. If you want to jump to a big 6 job (and a decent one, at that), then I'd probably try and find a team with a higher baseline prestige. Teams in Conf USA, MWC, MVC, A-10, Horizon, and MAC have higher baseline prestiges than other non-big 6 schools.
Also, it's easier to win the CT and get to the NT in an emptier conference. Conversely some enjoy playing in a fuller conference more than beating up on sims but if you go that route it's likely going to take longer to start making the post-season.
Here's a list of baseline prestiges for D1.