I'll be the nerd that digs in on fighting style.

John Wick is a practitioner of Brazilian Jiu-jitsu, which is a lot of grappling, positioning, and ground fighting.

Jason Bourne primarily uses a mix of Kali and Jeet Kune Do. Defensive postures and swift counterattack.

Ethan Hunt started out mostly with capoeira (flashy, acrobatic fighting) and shifted to Keysi Fighting Method (defensive postures and elbow or hammerfist responses) in later films.

All of this is dubious, because of the magic of filmmaking and how every fighter says their style is the best, but I'd say:

Hunt and Bourne would square off well in the opening round, but Bourne would win out.

If Bourne can keep his feet, he'd beat Wick, but if Wick can get him on the ground, shit's gonna go bad for Bourne.

Hunt versus Wick would be a mess, but Wick would roll it up in the end.

Three-way fight would go better for Hunt, since Keysi is designed with multiple opponents in mind and it multiple opponents plays more to Hunt's trickster tendencies, but Bourne is still going to win out just based on the level of violence in the methods.