choosing a training program

I want to sign up for a spring marathon and think I have one in mind. So tonight I've been looking at various marathon training programs. I don't have a tried & true that I've used in the past. I seem to use a different one every time and these last two marathons I followed my running group's plan. I've put their training program on my calendar again and it looks reasonable given the 9 weeks I have until the marathon. But I'm curious: how do you choose a training program? Do you have one specific one that you always go back to?