True for some but definitely not for me.🙂 I'm one of those odd people that finds walking outside for exercise very tedious and unrewarding because I just don't keep up the pace and I prefer my climate controlled exercise room with all of my music on tap and a variety of equipment to allow for variety. I do spend time outside, but not for exercise, and do agree it is good for the soul, but only if the weather is kind.🙄Back on topic, you wont use either they will both become clothes horses. If you can get outside do it, the fresh air and metal stimulation from being outside is fantastic and you will feel much better even if its just a 10 or 15 minute walk. If I had to choose it would be an exercise bike though.
I bought my treadmill Feb 2019 and it has been in constant use since then. It was the first piece of equipment that I bought when I decided to set up a gym room. Since I have added a rower, a stepper, a weights machine and an air bike. I use all of the machines from time to time but the treadmill and bike see more of my time.
I particularly like the treadmill because I can set an incline and a speed and even a time if I wish but I generally just rely on the display clock. Then I maintain my speed and enjoy the music. I'm not really one for earphones, I have never found any that come remotely close to a decent pair of speakers.
Having said that I do find the bike a close second as it's more versatile as I can do HIIT on it which I wouldn't try on my treadmill for safety reasons.