As said, there are a lot of good sources here. The best advice I can give is to try a couple and see what works best for you all around. You mentioned two, MLG and Olympus... You won't hear a single bad word come from either source about the other. MLG is a fine group with solid gear and reps who care. Of course Olympus would love to have you as a customer as would any other sources here. You almost can't go wrong with sources here on ASF. The hardest part of picking a sources is actually picking a source. But really you don't have to pick only one. The benefit of having a number of great sources is you can take some from each and over time find who you're really happy with.
Welcome to ASF.