The best advice is you should not focus on either.

Do high-intensity, heavy weight, low rep weight training to add muscle several days per week. I like to do mine on Monday, Wednesday, and Friday. I rotate between upper and lower body workouts each session. One week I do two upper body days and one lower body day, the following week it reverses.

On alternate days, you should do high-intensity cardio exercise. Most of my cardio exercise is on an exercise bike. I ride at intense levels for almost an hour, with sprints added at strategic times to push the heart a little harder. I do cardio on Tuesday, Thursday, and Saturday.

I am not a big fan of high rep weigh training, unless you are training for some type of athletic competition.