1. Can you use them anywhere other than the vending machines?
2. Which machines have the best prizes?
3. Is it more profitable to sell them outright or use them in the vending machine?

Please and thank you.

1. Yes. The Token Shop takes them, as well as various games in The Fair Grounds.
2. It depends what you want. Different machines give different items, but I think they all have the same rates of giving out rare stuff. Although the one in the Uncharted Island might be "best" simply because fewer people have access to it.
3. Using the tokens is a gamble. Selling is a set price, but the vended items vary. You could get stuff worth 500sP or 500,000sp. It all depends on your luck!

Personally, I store most of my tokens and spend some on a few machines. The Prize Get! and the one in the Valley give me the items I want most. I've never sold the tokens. Keeping them and using them to buy Token Shop items is much more profitable!

Thanks a lot!