Since the regular points have already been covered by other people, I’ll add one thing that I like:
Two batteries. The external one is drained first, and it can be replaced while the laptop is running, because there’s an internal battery. I have 24Wh internal, a 16Wh external (it’s old, originallly it was 24Wh) and 72Wh external, in a 12 inch laptop (achievable because 72Wh battery sticks out and acts like a stand), giving me more battery life than anything else without an external power bank.