I got a cheap metal link band with a Fossil style clasp for like $10 and I love it. Makes it look more like a fashionable mechanical watch instead of a spacey tech gadget.
Around the house, I use these super cheap stretch bands I found on Amazon from one of those random Chinese sellers that changes names every week. It was $10 for a pack of 3. I didn't expect them to be decent quality, but I've been pleasantly surprised that none of them have broken or rattle or anything even after about a year of use.
Whenever I go out or work out, I put on the stock silicone strap. I'd like to pick up some more at some point; the quick-release mechanism is really well-done and makes changing bands on the fly super fast and easy, and I'd love to have more options for different scenarios. I just wish the official bands weren't so pricey.