depends if you want to build muscle and be big, or stay smaller and fit...
Cardio = highers metabolism and loses fat
weights = strengthen muscles and lowers metabolism
me i'm smaller guy, so i want to gain weight. So what I do is carbo load like a mother fucker and lift a lot of weights. not so much cardio.
want to stay strong without all the weight gain, keep doing cardio like running and push ups and shit and don't lift as much weights
as a boxer you should balance between both, that's what I do as a MMA fighter