PocketCasts was pretty much perfect for me for a long time and recently (past couple years maybe?) they did a big update which made it noticeably worse. I tried a few other apps and they had even bigger issues. I'm still using PocketCasts and they've fixed some of what they messed up but it isn't perfect.
They have a good library of podcasts built in but also allow you to add custom rss feeds for any smaller shows they don't have or if you have private feeds from patreon or elsewhere.