Thanks everyone for your responses and suggestions! I have now tried 11 different mugs, from 7 different companies, including Contigo, Starbucks, BMW official merchandise, etc.
I can tell you, without a shadow of a doubt, that all of them absolutely suck in comparison to
the Thermos one I linked in my original post. I didn't realize how spoiled I was by this
truly vacuum insulated mug. I don't know why the idiotic graphic on Amazon says 5 hours HOT,
on their official website it says 9 hours HOT and I have come pretty close to it in real life (drinkable warm coffee after 12 hours). I have found a solution to the rattling (added a cardboard sleeve around it) and I will never complain about it again.