I think I read in a thread here that the Ultra Dream is a powder board that can do freeriding. The Cobra is also sort of a playful freeride board that is shaped specifically for powder. The Heritage is a twin shape (good for switch riding) and has a lot more dampening (which is good for when the snow is crappy/choppy) than the other two boards.
So one way to help decide is ask yourself where/when are you going to be using this new board? Personally, I typically ride park when the snow conditions are crappy as the groomed/raked snow there is actually decent... so while I was really eyeing the Heritage myself... MAYBE drop it off the list.
I'm eyeing another board...the YES Pick your line. Though, I am not sure if they have it at the board shop I went to so maybe it isn't an option.
I agree, I'm probably leaning towards the Cobra right now. It is pretty sick. I think the Ultra Dream is sick too, but it is probably going to throw me off with the different board style.