I use a Wavemaster XXL with 320lbs of sand in the bottom of it. Cost me $125 from a guy on Craigslist and about $28 in sand. Can be hit with full force kicks, punches and jump kicks if you are into that kind of thing. The only issue I had with the standard 150lb heavybag is that when I hit it with kicks I would have to wait for it to stop swinging to hit it again. If you aren't doing any kicks then a standard one is well. I think the B.O.B. is used for precision striking and is also good for accurate weapon strikes in how it feels to hit with a weapon and the recoil effect ( nunchaku ) from it but in Kendo we use a standard boxing heavy bag at about 300lbs and it hangs to the floor so it really is a matter of choice in what exactly you need it for now and what you may be doing in the future with it.