Your choice is simplified by the fact you want to fit disc brakes, must be a db version. I can't remember off-hand if quick release is the only version for the db version, or if there is a touring screw one as well. If you are having the frame built specifically for the rohloff, then have a suitable drop out used to allow you to use the oem version, then wheel removal and replacement is simplified. Also if you use the ex mech then this also makes wheel removal easy, and also removes those 0.9mm internal cables (I think the ex is the only version for the db models). Another thing you may want to use is the eccentric bottom bracket in your frame, then you don't need horizontal dropouts, and chain tension is very easy to set. Then there is the finish, silver, black, red, choose whatever takes your fancy.
When I got my raven discovery I was amazed at the simplicity of everything related to the rohloff hub, but I feel part of the simplicity is due to having a frame designed correctly to take advantages of all of these things, so make sure that the frame builder is thinking about these things as well, or you will need to choose different options on the hub.
From
Michael Whapples