I can sum this choice up for you OP. I had the RK front lower arms 2 years ago and they were ok, hard to adjust and the joint started to corrode.
Then I read all the hype about MC duroflex joints and how amazing the ride was. I installed a set of front lowers and have had them on about a year. The first thing I noticed after switching from the RK to MC arms was my steering felt looser with the MC arms, probably due to the rubber joint. I liked the more connected to the road feel with the RK joint.
So, I just ordered a set of EVO front lower arms, they haven't arrived yet, but I am confident they will be the best of both worlds and have never read a negative review on them, or any EVO Enforcer lift components. I have slowly swapped my entire suspension to EVO Enforcer based off great reviews. Hope that helps you make a decision!