Another vote for weights from personal experience.
I can skip cardio workouts when busy and not regress, but I always regress (gain weight / increase body fat % / look pudgier) when I am doing only 30-40 min cardio 4-5 times a week.
I also notice that cardio fitness is easier to work back to after a break than weight training.
Circuit style weight training or heavyish traditional weight training - both work for me.
This has been my experience since age 35. Before that, any exercise, even just cardio was good enough during busy periods.