Purely anecdotal, but I've been using a T450s for over five years and I don't see myself really upgrading anytime soon. If I do upgrade, chances are I'd get another ThinkPad. I like how little they can cost and how they don't conflict with Linux.
- XPS 13 is going to look way better, have better screen. But - Thinkpad, more comfortable keyboard, more ports, you don't mind throwing it around, and it's cheaper.
You can currently get a Thinkpad x13 AMD for about $750, tax included and it'll do all you need, minus playing games.
I don't know what comes with the Thinkpad you're looking, but make sure you get one with the newest Tiger Lake graphics, it's significantly better than Ice Lake and miles better than the 14nm stuff.
I did a trial with a T490s and settled on it. The keyboard is better on the ThinkPad and it doesn't suffer from the heat problems and screaming fans of the Dell XPS 13.