Not a client but check out the *arr[1] family if you're into self-hosting. What client you choose depends on your usage, I like Deluge. There's some initial work to setup and a little bit of maintenance but it's worth it, throw a Jellyfin instance into the mix and have all your media in one convenient place. Linuxserver[2] has containers for all of them.
Then I just search on various torrent sites. Thepiratebay.org and rutracker.org (use google). But movies and TV shows are easy to find. There are many sites which specialise in it.