I've had both gender dogs.
I've had two dobermans, first one was a male and he was massive which probably lead to his early death. so second one I got I got a female so she'd be smaller and hopefully less prone to dying young.
the male was super mellow and almost timid at times. my female was always on go mode "protecting" us from old ladies out front etc.
also always wanted attention, she thought she was a lap dog.
I don't really have a preference male or female though. I'll probably just keep getting rescue mutts now. all my purebred dogs seem to die super young from some stupid disease or cancer. mixed breed dogs seem healthier.