its the million dollar question mate, tbh i dont see that it matters what sex they are, its like saying do white fellas work better than black fellas? just depends on the ferrets mate, only thing i will say is tend to do more digging with hobs as they got a lot more weight behind them rabbits struggle to get past em, they way i work it is if i'm on a smal warren i use jills as they tend to work the warren quicker, but big warrens i get the hobs out aswelll just for extra man power, all depends on the situation