I'd go with the Seekins IMHO.
7 PRC is a good choice. Shoot heavy bullets like the 180 ELD M.
I've got the parts to build a 7-300 PRC, just waiting on the chamber reamer for my Smith to put it together. Wanted a little more horsepower than a 7 PRC since I already have a 7 mm Remington Magnum and a 280 Ai.