Any of the newer generation, recent jeep models will do. I believe they all have the M1 bracket mounted on the back of the windscreen as well. It really depends how detailed you want to be.
Meng’s Willys MB jeep is pretty nice. It is pretty well on details and an easy build. It includes the M1 Garand in the window mount in the kit.
Takom’s Willys MB also looks good and a pretty easy, well detailed build. It also includes the M1 Garand window mount.
Tamiya’s Willys MB is pretty nice, yet has simplified details in some areas. It is probably last in the order of newer Willys MB jeep kits. It also includes the M1 Garand window mount.
Bronco’s jeeps are also very nice. They are broken down into a lot of small part, but offer great details as well. But, they are Ford GPWs (jeeps license built by Ford), not Willys MBs. They are basically the same, with a few different parts that Ford used, such as an upside down U-shaped front frame cross member as opposed to Willys rounded tubular front cross member. Also many of the parts on GPWs will have F-script cast or stamped into them. Lastly, the impression for the rear toolbox opening button on a GPW were square and round on an MB.
http://www.missing-lynx.com/reviews/usa/broncocb35105reviewlp_1.html
The only ones I would stay away from is the Dragon Willys and the older Tamiya Willys w/trailer. Even the old Italeri jeep was pretty good, but not as good as the newer ones above.