After a quick look a the diagrams - if you plan to live aboard by yourself, the B is definitely better - you'll probably wind
up sleeping on one of the berths in the main salon
and use the aft berth as a catch-all for your stuff, although it is a pita to have to make and unmake your bed
every day so you may well use the aft cabin
for that reason. One bad point about forward heads is that they are more challenging to use when under way because the extreme bow of the boat tends to have the most vertical motion (picture yourself straddling a bucking bronco while going about your business), but I not that the head is well forward on the other design, too, so it is moot. Both galleys look workable.
On the other hand, if you will have a female mate aboard, the A layout might be more suitable merely because it has that nice big V-berth to use as opposed to, again, using the "double" in the main salon
and having to make and unmake it every day.