Brendan O'Brien rules.
The Battle of Los Angeles by Rage Against the Machine is one of my favorite albums ever, and was also produced and mix by him.
While it's not the best mix from a technical standpoint (quite a too middy on the guitars), it somehow just suits the vibe of the band.
A lot of that alternative metal stuff had great production though, around that period.
Linkin Park, Evanescence, Limp Bizkit, Deftones, Korn etc etc.
Part of the sound is just tight musicianship too.
A lot of the guitar players, bassists, and drummers in these bands were probably honing this chops on thrash metal rhythm guitar before they joined these bands, so they could play well. Definitely musicians that came from an era of having to know how to play tight, because it was before they knew they could be "fixed in the mix" as it seems to be done these days for 75 per cent of metal bands that walk into a studio.
It may have not been super technical music, but being able to just play perfectly and nail each take, is superior musicianship than to trying to play technical death metal and totally failing.
Definitely well produced. Guys on the production team, tracking, mixing, mastering and production, generally many of the best in the business of course. As far as metal genres go at the time, the tracking for alternative metal at the time ruled. The guitar sounds and bass sounds were just at the peak of all metal sounds at the time really
Yet as was said, still natural sounding in a way and love how vibey it is.
Polished, yet with huge aggressive sounds that were also smooth and pleasing to the ear.
Now the hunt is on for instrumental Limp Bizkit (while I really dig Amy Lee's voice in Evanescence, I too don't really gel well with Durst's voice
)