I would lean towards the .300 Norma. By mid-2019 there will be Lapua, Peterson, ADG, Bertram, and Norma brass all available for this cartridge. With the .30 Nosler you're currently limited to Nosler brass, which is decent brass but doesn't hold up to pressure for very long. Bertram says they are working on .30 Nosler brass, so that should help.
The .300 PRC looks pretty good as well. Ballistically it's identical to the .30 Nosler. What advantages I see with the PRC is first off it's SAAMI reamer design was made perfect for 220-230gr bullets with a match style chamber. Hornady designed it to work in today's 3.6"-3.7" magazine boxes found in long action rifles. Nosler on the other hand designed the .30 Nosler around the 3.4" magazine in their line of rifles. That really shot them in the foot. Now you have to special order a reamer for a longer freebore, or have your smith lengthen the throat if you plan to shoot heavy, high BC bullets in the Nosler with proper seating depth. The PRC will suffer from Hornady brass, unless Hornady steps up their game and makes decent brass that lasts, like they have done on occasion before. I feel like Hornady's marketing will pay off and you'll start to see brass manufacturers pick up on the .300 PRC just like they did with the Creedmoor and they're going to do with the 6.5 PRC.