Flail Mower Tractor Attachment: Brush Hog Vs. Flail Mower?

Tractor attachment: Brush Hog vs. Flail Mower? - flail mower

For 5 + acres of land with only grass and weeds (brushless), which is better, a brush or brush hog? I can hear the brush has a better job covering and provides a clean cut.

Any information is appreciated.