Have a friend play patrol on any planet once so u can enter the different Planets (if that doesn't work do all the hub missions that set you away to them) and patrol everywhere u like the scenery best. There is not a "best" spot to patrol, every patrol mission is the same... On the moon u have quick missions because the moon is pretty small but on Venus the counter for collecting stuff and kill seems to be quicker... I dunno if that is right though. But as I said, go patrol where u like it best, exp outcome is the same and loot too.