As our readers know, we view what most people term "cardio" as about 1/3 of the general fitness triad (resistance, calisthenics, and cardio).
Among the machine options, the rower and the stair machines are most designed to help build some strength along with the heart stress. The advantage of the rower is that it is pretty much total body, and when you up the resistance, it's some strength along with the cardio.
To beat a dead horse, cardio is meant to be about heart fitness, so if your heart rate is not where you want it then all it is about is physical endurance (which is not a bad thing in itself).
The Maggie's protocol advises sprints for cardiac fitness, not long-slow. Long-slow, like walking or swimming laps, is fine for ordinary endurance and maintenance. It all depends on one's goals.
I like mixing up my cardio days with variety to avoid boredom. Treadmill sprints, rower, stair machine, ski machine. Usually only 30 minutes, then I finish my hour with accessory weights.
Reminder for January fitness people: unless you are a unicorn, do not use exercise to lose weight. That's not what it is for, and it only works for the rare unicorn. Exercise can be good for muscle weight gain, though, especially weight training. Losing fat is about nutrition.
