Finally got this thing to work! You're going to be hearing a lot more from me now.
So, I refuse to pick just one, but I'll give you two.
If we're talking "hot sauces you can find in a grocery story", I think Valentina is the GOAT. It's flavourful, versatile, and delicious, and nowadays I can find it anywhere. Though the flavour is mainly mexican, it's able to fit with many other food types.
If we're talking "hot sauces nobody else here is going to find", one of the first hot sauces I made was a fermented leek and ghost pepper sauce that I have never been able to completely recreate. I dream about it sometimes. I miss you, Pandora's Bottle.
Also, I have a favourite sauce from a local sauce maker but it's a small enough company that if I name it, I'll doxx myself. DM me for more info.