That is really hard to answer. I´m going to say what I like to do but idk if it's the best option to every one.
OBS; I'm RP
First I highly recomend recommend to open the third prey window. Than roll them until u get XP 10stars. When I get a mosnter monster that I use to hunt, I don't use the prey immediately, I keep it to the next day, so I can use and before it to finish (2h) I select to reroll the monsters. This way I always keep 10 stars of XP.
But if you are MS or ED, for example, some hunts are better u roll and get 10 stars of loot. If u you are knight and will hunt the new skelentos u skeletons you might roll and get 10 of defense. As RP I always use XP until now.