Moon Direct probably makes the most sense. It needs only the Falcon Heavy (about $150 million per launch) as a booster. That's a real rocket that's flown. No need for NASA's vaporware Space Lanch System ($14 billion spent so far over 8 years, still unfinished, zero launches.)
Apollo did it with one giant launch, but now that assembling systems in orbit has been done many times, there's no real reason to build something the size of the Saturn V again.