For HD content, the best one is BeyondHD (framestor releases).
Torrentdb.net also has decent quantity of framestor remuxes, u would be surprised, just give it a try.

PrivateHD is also a decent HD tracker, since once u get PrivateHD, u can even join their sister site, cinemaz, for old rare, obsure, classic movies.

See, let me give u another piece of advise, if u r just looking for collecting trackers, then u can give the above trackers a go, otherwise if u r genuinely looking for HD remuxes, Torrentleech has loads of them, TL is best in my opinion for HD, 4k or UHD remuxes. Mostly i am able to find the 1990s or older HD remuxes at TL well seeded on seedboxes and that too freeleech. There have been moments when i had to go look for an old movie remux on PrivateHD, Blutopia, BeyondHD since TL was missing that remux but its kinda very rare, 95% HD remuxes are available at TL.

I have tried rutracker as well, if u have a blazing fast internet or seedbox, u wont find good speeds there, speed looked garbage to me, i have 75mbps home connection, TL is ur best bet, they literally surpise me with so much remuxes available and that too very well seeded.