I only use mine when it's icy outside, and it's got a lot of miles on it - but it still runs like a champ.

If I were shopping for one, I'd look for one that was basically a high end one from ten years ago that's been used as a clothes hanger. There tend to be a lot of those around.

Nice to have features: built in fan at chest height. A built-in folder for a tablet that is mounted at eye level. built-in speakers and a headphone jack.

The proform people had a good era where they were doing that for a while, then they went nuts and just started to make gigantic screens in the treadmills themselves and try to sell their subscription service where you can run along with videos of other runners in exotic locations... but when they made those screens gigantic they also took out their phone / tablet holders because "who would pay for a subscription to not be bored running when they could just watch their existing subscriptions for free on a tablet"