I know you are looking for a simple answer, but there is not one. Like almost all things boat the answer is IT DEPENDS. It depends not only on the specifics of the individual design, but on exactly how you will use the boat.
USUALLY (but not always) a forward berth has better air flow and ventilation than a cabin in the back.
ALMOST always (but not always!) a forward berth is less comfortable underway than one aft.
Most (but not all) designs with master cabins aft have more room in the cabin than do forward cabins. The tapering of the bow just makes this the way things usually work
One thing I can say "always" about is all normal cruisers spend much more time at anchor than underway.
Boats sailed by couples will not have both members of the crew asleep at the same time underway, so sleeping arrangements while underway can be different than while at anchor without issue. A single
pilot berth can work
fine underway, even if it would not be acceptable while anchored.
On a sailboat, or even a motorboat, a walkaround centerline berth is pretty damn useless underway. You will roll out onto the cabin sole! Looks great at the boat show
Boat designs vary so much that any rule
about THIS being better than THAT is just not worthwhile as a generalization. You really have to look at each design and evaluate it on its own merits.