"Best" is probably going to be private torrent trackers.
But if you meant public torrent indexers then the top ones in terms of web traffic are 1337x, ruTracker, TPB, Rutor, & TorrentGalaxy.
Most people that were using RARBG have ended up at 1337x and TorrentGalaxy.
For what it's worth if you just need a website to search the old RARBG torrents https://rarbg.best might be a good fit.
PS A lot of these sites are also linked at the other torrent site community [email protected]