I have 2 in the XPS line - a relatively old 15 inch and a new(ish) 13 inch.
They're perfectly fine machines.
Dell officially supports linux on them (admittedly, only Ubuntu), you can get 32gb of RAM, and they perform just as well as any other intel based laptop (which is to say - I wish they sucked less power, but they're fine on the performance scale).
I'm... not a clean person with my machines, and I've never noticed any issues with the keyboards.
I have zero issues swapping wireless to wired (Arch linux) - it's basically instant for me, but I don't actually know how you're testing that, since none of the newer 13 models include an ethernet port (I use an adapter). Have you considered that you have a bad usb-ethernet adapter? Every one I've used is fine. Alternatively - are you sure you're not thinking of the Latitude line? Those are very different machines, which I also avoid.
Basically - I'd take an XPS every time over anything Lenovo puts out. I don't even really care about the hardware, I just think Lenovo can't be trusted a god damn inch. Chinese company selling computers with rootkits/MITM pre-installed. It was a sad day when IBM sold their personal computing line to them. I know a lot of folks still like the Thinkpads - but it's not worth it, IMO.