Recommendation for Thermos for Work (450ml to 1. 25L)

Looking for Thermos for work mostly.

Anyone to avoid or what's the gold standard in this field.

Size between 450mL and 1.25L leaning on the smaller side I guess just big enough to fit the largest size coffee.

Mainly to just quiet co workers who keep telling me to bring a keep cup or reusable cup and I should have one at least on hand just in case.

Asking in case there are any models or brands that people have found to not be good or if there is a good one everyone agrees on.

Cheers thanks.