I remember hearing something about a bitcoin credit card. Like, one that you pay for everything with fiat on credit, and then you pay off your bill in bitcoin. So you never have to hold fiat if you don't want to.
What's the best/most reliable credit card that does this?
I'd say either Wirex or Xapo.
Maybe Coinsbank, but I have never used them myself so I can't really comment on their quality of their product or anything like that. I've only touched Xapo which has worked for me every time if you are willing to provide some ID, and Wirex is one of the oldest anonymous CC providers around, you don't even need to submit your ID.
They were called e-coin before they rebranded.
If you want to pay your bills, look onto localbitcoins. In my country there are always offers to pay your bills for bitcoin on there, and for a pretty good price as well.
I think you understood wrong about XAPO because they never allow you to spend first and then you can pay them instead you need to load bitcoins first and then you can use their debit cards for purchases or you can even withdraw fiat currency from ATMs. But remember each and every transaction using these cards will have some fee and sometimes it may be quite high you're doing a small amount transactions. I use this card for urgent cash withdrawal from ATM's but never purchased anything online yet, and you can also use this card to your PayPal account.