The closest thing to a NR AR15 like platform is the MS hands down. I dont see how the PAR would even make the list of a NR AR15, The MV has lots of Proprietary parts due to its design, The SLR would be the 2nd closest but at the price point they sell them you might as well get the MV and skip having to mess around fitting Geissele triggers into the trigger box and dealing with parts that may or may not fit.
for AR10s the Stag 10 is the way to go, everything fits and there is no proprietary parts. The BCL102 Gen 1 stripped set was cool and had zero issues with mine except for the cheaper finish. But now the new BCL stuff as seen on their webpage is filled with proprietary parts so you cant even change things on your rifle to fit your needs. But it does seem QC was stepped up big time ! I might be wrong so Im actually looking forward to handling one to see how these handguards are mounted.
I hope this is a better explanation on what I see in the NR AR world. To me a AR15/AR10 is a lego set you can customize how you see fit. Yes the MV is a fine piece of kit, Ive shot them and they are super nice but never bought one because it didnt fit the NR AR role i was looking for, And I dont think I was the only one seeing how many guys ordered up the MS even before we had a FRT! I built 3 BCL102 and I had to do lots of fitting and lots of testing to get them to work properly, witch is unfortunate as I really wanted to give NEA a 2nd chance.