I guess the it’s the always irritating answer of…. it depends.
For me it I just try to be as sport specific as possible which is a recurring theme in these forums I have found.
In the spring I use the treadmill alot to get in shape for trail running (when I have to be indoors that is).
In the fall I have a big pack and go up and down my garage stairs. If it was a machine I think the step mill is the best answer but they are very expensive and not every gym has them.
The “star masters” with the rotating feet I think are the least specific and realistic. They can get your going for Z1 and Z2 but your legs aren’t getting the same workload. Better than nothing though.
Jake