I squeezed 15K miles out of the stock chain, but it should have been replaced sooner. I replaced it with a DID VM. I replaced it 21K later. I probably could have left on longer, but I was getting ready for a 4-day trip and didn't want to chance any chain problems away from any metro area. I replaced it with a ZVM, but that one's only been on for a couple thou, so it's too early to tell if it will outlast the VM or not.
If you use a chain luber, you will get more miles out of a chain than any of the spray-on lubes or waxes.
Unless the sprockets look GREAT, replace them both.
I can't speak good or bad about other brands since I don't have any experience with them. DID's came recommended to me years ago and I've always stuck with them. I've seen on other sites that DID is the brand with the most "highly recommended" comments, so I've never had a reason to risk using something else.