Honestly? If you intend on the rifle serving some role as a selfdefense rifle then I would not go with a Wilson Combat or JP Enterprises upper, both likely are made to more restricting tolerances that might turn around to bite a person in the butt some day down the line when it really counts. I would look more towards a Bushmaster Vmatch type upper assembly where having it's barrel built to milspec it will likely run a wider variety of ammo more reliably than the JP or Wilson Combat uppers while the freefloated handguard would allow for a bit more consistent accuracy than regular handguards would allow for. And in most situations the Vmatches will still allow for enough accuracy to run well in the 3gun or tactical matches after either irons or optics are selected that are appropriate to the match.
If you were going for an ultimate varmint AR15 or just a game gun then I'd suggest folks like JP Enterprises, Metalcraft, DPMS, as well as a couple others but when I think of picking up an AR15 and counting on it to be reliable I goto one of my more MilSpec setups rather than turn to my tweaked and accurized JP gun.