Portables:
Used 80s-90s players are probably the best bet for reliability, quality, and repairability. Regardless of brand, if a working one pops up on FB Marketplace or in a shop ~$20, it's worth picking it up and giving it a quick cleaning to see if it works for you. If you want to spend a bit more, Sony Walkmans are definitely the standard. Techmoan's Sony Walkman Buyer's Guide is a good reference, and he goes over which ones can be easily fixed and which ones are doomed to break. There are some newer products like WeAreRewind that even support Bluetooth, but I don't have experience with them (if anyone does, I'm very curious!)
Stereo Decks:
Tape decks can be pretty affordable if you come across them at yard sales or Marketplace. Here's a primer guide on those. Most would say to stay away from the dual-cassette decks (the ones used for dubbing from one tape to another) because they were all made pretty cheaply. Nakamichis vary widely from affordable to expensive, but they're all really great.