My first choice has been a SR25 for decades,
BUT,
I've been messing with my new MR762 for about 3 months and I may have a new favorite.

All my SR25s needed changes in gas volume when I screwed a can on, and no guarantee it would cycle at all with subsonic rounds,
The MR762 doesn't need any changes, and it's cycled virtually everything I've fed it so far, but I only have about 3 subsonic loads I shoot.

I'm still looking for 'THAT' load for it, we all know how that goes, but it shot MOA groups out of the box with off the shelf match grade .308 win and it's getting tighter with hand loads, but I haven't had a lot of time to develope the loads.

When I'm not tired or overheated (miserable here),
It's down to around 5/8 MOA in my best groups, and that's fine for what I do and the ranges I shoot on the loads that worked in my SR25s.
This actually surprised me, I figured it would be a crap fight to get tighter than factory match ammo, but it did well.
(178 grain Hornady with Varget, 2,850-ish at the muzzle, reconditioned milbrass, and yes I know about Varget/heavy bullet/7.62 milbrass in a .308)

I bought two and both shoot similar, which surprised me, HK can apparently make a consistent production barrel now, which wasn't always the case...
I bought them when they got ordered and never picked up, enough paid down to allow for a custom barrel but I don't need one!
It made this an even better deal, which I never seem to find...

*IF* anyone is considering buying one, get the latest updated version, they solved the hammering recoil issue...
The buffer doesn't bottom out now, much easier to stay on target.

I can't speak for anyone else, but if you have an AR-10/Clone, SR25, etc. You already know how hot the gas system/bolt gets in rapid fire, and this evolution doesn't do that nearly as much, not nearly as much heat related upper receiver expansion, and the sighting/cycling issues that can cause when everything is tight...
I'm enjoying mine (when it's fit to shoot outside) and hope this helps anyone thinking about one.