The bigger one.
I don’t that often take it anywhere except by car, so the slight weight increase isn’t an issue (although now I think of it I must check if my laptop sleeve will still fit; I think it will as it’s too big for the old one).
I probably wouldn’t have bothered, but the old one has developed an irritating glitch of refusing to switch on when not plugged in (and occasionally shutting down when asleep even when it is), which I strongly suspect is due to some sort of secondary battery having died. If I still lived fifteen minutes from an authorised repair shop….