i prefer heavy bag, most bobs are girls and break down too easy ,it was funny to try out bob ,but with gloves it isnt the big difference for me hitting a “face” or just the bag, and without gloves for targetting practice i am usually focusing on wrinkles wich appear thru punching, or u can also use little colour stickers to hit for targetting practice ,if u have a trainingspartner he could give u commands to train a little stress ,to cause even more stress u can switch commands then (red u hit yellow ,.....) : )
so all in all i prefer good old heavy bag ,it is more honest in my opinion. greetings from vienna