I occasionally make similar whisky-based truffles. I'm normally a great fan of peaty whiskeys (e.g. Islay), and I once used Caol Ila. The smokey flavour did not work well with the chocolate.
Therefore I would (personally) recommend against using something peaty/smoky.
Honestly, "whatever you want" is the only answer :)
I have a similar seasonal recipe, and in various years, have tried:
And so on...
The flavors of your chosen liqueur will be somewhat muted by the chocolate, and so something with the complexity of Drambuie was a bit of a waste. However, ultra-cheap ...
I suggest using a regular bourbon; one that you can drink after you open a bottle for the recipe.
If you don't drink the stuff, and just want some for the recipe, get the cheap one in small bottles, enough for 1/2 cup.