The business Dell laptops blow anything lenovo has ever made out of the water in terms of specs, build quality, and serviceability. Also Dell’s bios is way better and easier to do stuff in. I’ve had a t420 and I thought it was crap compared to the Dell business laptops. The cooling, plastic casing material, and serviceability just isn’t there. On the T420 my palm rest cracked and to replace it you pretty much had to fully take apart the laptop to get it off. ifixit rated that particular repair at a pretty high difficulty, so instead I took the reusable components out, binned it, and used a Dell latitude.
Currently I don't own a Dell business laptop however. Right now I'm using an Intel NUC Laptop and it does pretty good.