Thinkpad is lighter/smaller, nobody has the x1 carbon beat for that.
If you're looking at other Thinkpads, the Librem machines may be worth investigating.
I'm not sure how well they run operating systems that run non-free software (this includes Ubuntu, note), they have some OS of their own?
If you want dumb-proof, tested Ubuntu-tops, then yea, Thinkpad.
Have to admit my gut is to trust the Thinkpads more simply due to the number of units they ship. Librem seems super niche, despite me loving their goals/etc.