If I had my druthers I'd have one of each. If I could choose just one I'd take the rough cut flail. Easier to manuver and store (but the bush hog's ability to back under bushes is lost). The bush hog requires less maintenance. Flail needs to be greased each day and while a bush hog's blade will likely never be touched, flails need turning or replacing every few years. As others have noted the flail cuts much finer and mulches. No sharp sticks left behind if you do mow over a bush with a flail. One other advantage if you mow near a road, dwellings or people is that the flail virtually never throws anything out while the bush hog does eject high velocity projectiles on a regular basis.