I've been discussing it with my friends and we really don't agree. For the following sets of assets and flaws, for BOTH genders IN YOUR OPINION. Skills are also a huge factor when picking a partner these days, so I suppose those should be factored in as well as stat caps/class options. You could always just say which folks you paired with your MUs too.
All the stats that most people use: +STR / -MAG +STR / -LUK + MAG / -STR +MAG / -LUK +SPEED / -LUK +SPEED / -MAG +SPEED / - STR +DEF / -LUK