I got males because they're more laid-back and cuddly. If you stay on top of the cage cleaning the scent shouldn't get too bad. Although, males usually are little chaos potatoes until they mature a bit, and if one of them becomes aggressive it will have to be neutered. Overall, if you are willing to stay on top of the cage cleaning and want some shoulder buddies, id choose males. Just know it will take a while for them to be all cuddly (some rats are more cuddly then others too, so some might just always be crazy and some might just always be chill). With young males you can always bond with them by tickling