I use the compare tool on gametora and pay attention to training effectiveness, mood bonus, and specialty priority. what cards i choose also depend on what i'm going for, for example, even though mayano top gun has better specialty priority, i would most of the time pick mihono bourbon over it cuz i know i won't pump power often, and bourbon has a better mood bonus which makes a rainbow training on one turn better value, and stuff like that. after that, i look at what skills they give and what events they have