For toughness, you can't beat Motorola products. The business band radios I have used are Motorola Radius and they take a beating. I have used them in foundries where they got dropped all the time and never failed. I have had Motorola pagers go through wash machines and dryers and still work. My Nextel I60 got washed a couple times too, and never failed.
Next up to dependability would be Yaesu R series. I have an FT-50RD that has taken several spills of my belt, once it hit the concrete so hard it knocked the battery off it and but a fair sized gouge in the case, I just put the battery back on and it worked. One time it fell off my belt and skidded across the concrete and scratched the display all up. It worked fine and I used a polish made for plastic to fix the display.
Any tough radio will be expensive. The Radius rigs run 500 bucks or better per copy. They are business band radios and a license is needed and the FCC does enforce the rules on the business bands.