I am using Tiger brand. I can't believe it...I put 98 degree celcius hot water into the container for 24 hours and I can still pour warm water from it. Impressive! So I guess this brand is good to keep hot/cold food. I got it from Wing On when there were 20% off discount.
I am not too sure about the big 保暖壺 for congee, I only bought the one for water (long tall shape).
Here is their site:
http://www.usa.tiger-corporation.com/commodity/stainless_steel/index.html