Who do you plan to speak French with? I think that will help determine which accent you might want to focus on. For me it's less about accent and more about local idioms, customs etc. I live in Canada and in close proximity to French Canadians, so for me it's important to understand how they speak French. Even within a given area, you will still hear many accents, so it's hard to pin point any particular one. Ideally you should be able to understand people with various accents, though admittedly some may be trickier than others.

If you don't have any immediate plans to interact with people from a particular region, I guess the best would be to start with a "standard French" as suggested by Bernhard.