Personally, I'd rate Tomei highest, followed closely by Nitton Sine Drive, PRP would probably be slightly better then N1. Not sure how they've managed their R&D, I'm guessing its a Nitto copy.
A good friend of mines running a very similar motor(RB30 with extended sump and restrictors), hes running a Nitto oil pump, and I'm running a Tomei. We both run the same oil - I get slightly higher oil pressure at any oil given oil temp. Not saying that having higher op is 'better', but that's just an observation.