Axial blew the roof off of the crawling sector when they introduced their AX10 Scorpion Crawler. They have since gone on to easily become the biggest name in R/C Rock Crawling.
RC4WD has established themselves as a market leader in all things scale offroad. Anything from scale tow hooks to amazingly detailed, officially licensed tires can be found in their product lineup.
One of the largest all-around hobby companies in the world, Tamiya is the standard for scale realism and high quality that all other hobby companies are judged by.