Custodian Selection for Beginner RIA

Hey everybody, I'm in the process of registering my RIA with the state of PA, and going independent from the ground up (0 clients & 0 AUM). Currently I'm in the process of deciding on what custodian to select, and I have had fruitful conversations with a couple B/Ds. I talked with Trade PMR and really liked their Fusion platform, but they are looking for 2.5m AUM. I also had a good conversation with MoneyBlock, and I'm looking at Scottrade as well. Can anyone provide any insight/comparison on either of these two B/Ds, or introduce me new ones? Obviously, Im greatly limited by the AUM minimums so any guidance would be greatly appreciated. Thanks!