I guess if we are going to talk about bragging rights in Baja we should also mention that the GBC Grimm Reaper was the first tire to win the Baja 1000 on the Bi-polar Arctic Cat.
I would recommend an 8-ply tire for desert racing to help hold up to the environments. GBC offers both the Grimm Reaper and Dirt Commander in an 8ply with a combination of 12" and 14" sizes. If you are going to run a 12 inch wheel run a 26" tire. If you think you need to run a 14" wheel run at least a 27" tire. A 26" tire on a 14" wheel won't give you enough sidewall and will bottom out right into the rim crushing any wheel.
When it comes to wheels look for something that is strong! OMF Performance's Billet Center Wheels and Walker Evans wheels seem to hold up really well. Another good thing to add to your wheels is an inner reinforcing ring that will help stiffen the inner bead.