Contigo AutoSeal Thermal Mugs. They never spilled their contents, which I could never say about other thermal mugs. They keep everything warm/cold for a good amount of time. I’m just super happy with it, and it still holds up after 8 years of frequent, almost daily use.
https://www.mycontigo.com/products/thermal-mugs/west-loop-autoseal-travel-mug-470-ml/SAP_2095796.html Well, at least that is the model that looks like mine. The brand name changed from AutoSeal to Contigo in the last years, so it might be a bit different to mine, but function-wise it looks the same.