Far and away the best travel mug I’ve used is the Contigo Autoseal Stainless Steel Mug. The Autoseal mechanism is the most leak-proof design I’ve found; it seals automatically when you’re not actively drinking from it, so there’s no worry about knocking it over with the top open. This is the only mug I’ll use around my computers now.
I had a terrible experience with the Oxo mug. It was impossible to clean due to the enclosed design of the lid, and eventually accumulated way too much gunk inside for me to be comfortable using it. The lid on Contigo’s mug is fairly open and easy to clean, and the entire thing is dishwasher safe, though they also sell a model with a colored body that isn’t. They sell replacement lids for $7 if you have a problem, but I’ve been using four of them for over a year in heavy rotation with no issues.
Contigo also makes plastic smaller containers for kids and larger water bottles (both of which are BPA-free) with the same Autoseal design.
[Note: Contigo offers affordable replacement lids for all their mugs as well as specialized brushed to help with cleaning.--OH]