I walk on golf ball sized gravel every day for approximately 2 miles total. It is the death of any shoe, and tennis shoes last a few months at best here. If you say work boots I will assume safety toe.
I don't wear high rise boots, but for mid rise the best thing I personally have had is a set of Redback mid height pull-ons. Damn things lasted 2 years, and I tossed them only because I wore through the entire outer sole to the spongy insole. Very comfortable, and wear wonderfully. Sizes are boot sizes, not sneaker sizes.
As far as low rise I have a set of the all leather Timberland Pros. They are comfortable but I feel they don't breathe very well. I refuse to wear them until it gets under 80F and I can use some thicker socks to help keep air around my foot. They have lasted about 6 months though and the sole has worn very well. Their sizes are a little off as well. I wear a 10.5, but these are actually 10.5 wides and are smaller then the Sketchers and the Redbacks as far as fit goes.
By far my favorite pair of low rise safety shoes is Sketchers. Rated for electrical hazard, rediculously comfortable insole and breathe very well. Going on 8 months of those. Very grippy and wear very well...just starting to smooth over some of the sole on the heel but still great traction even when the sole is coated in aircraft hydraulic fluid.
I came out here with a pair of Wolverines, and some other crappy boots. They lasted a month or so because of the rocks chewing the soles apart. I ordered new boots immediately.
Several guys out here wear Keens, and they love them honestly. Little too flashy color wise for my taste. Nautilus is also another brand worn by many out here. We have to wear our boots for over 13 hours a day, 7 days a week, 52 weeks a year. Shoe comfort is paramount to us. A bit of advice, if you want to wear boots all the time, get 2 pairs and swap them out every other day. It will keep them from getting funky, and if there is a spot that wears funny on your foot with one boot, it probably wont on the other, saving your foot.