The definition for "go-to" that I'm interested in is: "Denoting a person or thing that may be relied on or is regularly sought out in a particular situation." (Source: Google's definition) I want a more formal word for this, but I couldn't find synonyms in any of the online dictionaries that had "go-to".
Example sentence: Jet skis are the go-to watercraft for exhilarating beach entertainment.
What would be a more formal substitute for "go-to" in situations like that? "principal" perhaps? But I feel like "go-to" has a different connotation than "principal".