I never understood why XFCE is not the default for Ubuntu desktop. It was(is?) part of Xubuntu, the lightweight Ubuntu distro, years ago. I had the most basic entry level laptop, but I managed to connect 2 external monitors to it while the tiling would remember the locations of all programs in all three monitors and it was FAST. Nothing I have tried since has touched it. It set me up for a lot of disappointment! I now have a macbook and while it's a great and integrated machine, CMD-tab - which I use to switch screens - doesn't even work properly if an application is in fullscreen mode.
On what Distro though? What should I try if I want something that pretty much works out of the box i.e. has acceptable battery life + WiFi + Sound + Suspend mode on a Macbook / Latitude / Thinkpad without me having to set up config files according to all kinds of internet sources for a day... or even a week?
XFCE is very stable so it should work almost exactly the same on every distro. Just pick the one that you like the most / is easier to install for you / etc.
KDE is a bigger and more complex system so it works a bit differently depending on what distribution you use. Some distros like KDE Neon always have the most recent KDE while other like OpenSUSE Leap prefer to use stable versions of the applications.
When it comes to wifi/sound/etc it has to do with whether the driver for that contains binary blobs. Some distros don't ship blobs due to security and/or software freedom concerns while other distros have a more relaxed policy when it comes to proprietary software.
Thinkpads have a reputation for being very easy to run Linux on. You should expect everything to work out of the box. For the Dell computer you might have to install drivers separately but you can't tell for sure without knowing the exact model you have. You could do a test drive with a Live USB to check out. I wouldn't expect things to work out of the box on the macbook though. Apple isn't very Linux friendly and their macbooks have many specialized components that are only found on Apple products so Linux support is not very good. But even then, some dedicated hackers still try to reverse engineer them so you might have better support if you have an older model instead of the latest macbook.
The following table can help a bit with determining if wifi will work on your computer:
Just works, anyone can use it, and if you wish, you can right-click on anything and have tenthousand config options to make everything exactly as customized as you want it.
And it works. No flashy in your face features trying to impress you with bouncing balls or animations, it's just like an improved version of Windows 2000 interface.
