I prefer the Trudeau ones. Sure, they don’t fit in a standard cupholder (they are wider than a soda can) but they are insulated aluminum and when you give the little knob in the top a ¼-turn, they will not leak. If you ever saw the way the top is designed, you would know why. And they keep a 14-oz. load of coffe warm or soda cold for quite a while.
I used to have a nice, straight-sided black cylinder one, but I lost it somewhere and have yet to find another exactly like it. My current one is a wavy-sided brushed aluminum jobber with a rubber pad that goes most of the way around the middle; slightly artsy-looking.
Personally, I think it’s great that I can throw the thing in my backpack with a bunch of books and not have to worry about getting a single drop of moisture on the paper, even if the cup is full of Pepsi. Most travel mugs can’t handle that sort of pressure without leaking, but my Trudeau can. The only issue I have with it is that, if I have soda in there, it won’t always open; the air pressure will keep the rubber seal closed unless/until you unscrew the top enough to release the air pressure holding the lid shut.