Currently, I’m leaning towards the Lenovo but I’m note entirely sure. I’ve used a Mac before so the different OS shouldn’t be an issue. Additional downside of the Mac is that the rotation period is 4y, whereas it is 3y on the Windows platform.
Assuming your workload will run on both, get the mac:
Better trackpad, screen. Better materials in general - a 4 year old macbook will still look pretty new if you don’t trash it - aluminium doesn’t go shiny in places where your hands rest like with a plastic PC laptop. The OS will also run as well as it did originally pretty much. Macs don’t tend to accumulate deeply ingrained shitware like Windows installs tend to over time.
Less annoying operating system once you adjust (background apps don’t jump to the foreground and steal your focus, mission control shits on anything windows has, mac gesture support is the shit, folder actions are great, as is automator and scripting).
Macs are generally good for 4 years, i’ve got a 9 year old macbook pro 15" that would still run fine if only it hadn’t suffered AMD GPU failure somewhere around 4-5 years old.
I’d say for dev stuff definitely go mac - you can easily run windows linux and macos (plus develop for iOS/ipadOS/tvOS/etc.) on the single machine.
if in doubt see if you can sit down and play with an example of both for a little bit. the difference in materials, screen, trackpad, etc. on the mac will likely sway you i would think, especially if you’re already curious about macOS.
I was PC exclusive between 1992 (as a kid) and 2009, then started buying mac laptops (desktops are still PC) for my own use and haven’t looked back.