There isn't a "right actor" for a Predator film. But I can't think of choices more erroneous than the likes that others have suggest ad infinitum: Karl Urban, Gerard Butler, Dolph Lundgren, Michael Biehn, et al. Any has-been(Biehn), non box office draw(all of the aforementioned), one hit wonder, or C-grade action star should be nowhere near Predator. They'd dilute the quality and would actually need the movie, and would be begging to even serve coffee on the set.
The whole point of being an actor is having a diverse oeuvre, doing drama and comedy, etc. Gosling is awesome, and especially so in DRIVE. Cooper is awesome, and especially so in AMERICAN SNIPER. And they can actually open movies. Especially Cooper.
Guys, there hasn't been a "macho man" Predator movie since the original movie. The movies since have been anything but the 'sweat n' muscles' conceit.
Give me actual actors with actual gravitas over these John Cena recommendations any day. Heck, get Dwayne Johnson. He's too obvious a choice and doesn't have gravitas but he can open a movie and would be appreciated at this point.