Originally Posted by Jason F in Los Angeles

i had two different versions of the Bodum glass teapot and I found that
they stained too easily. The first had a plastic infuser which got ugly
rather quickly. The second had a metal infuser, but even still the
glass yellowed no matter how much I cleaned it. Glass teapots are
pretty, and it's very cool to watch the tea brew, but a ceramic or
porcelain teapot is better presentation in the long run.

Avoid yixing unless you know how to take care of it. Avoid tetsubin
(japanese enameled cast iron) if you plan on cleaning your teapot with
soap. Avoid earthenware, as it tends to eventually crack and discolor.
Porcelain, I think, is the best bet for a beautiful, long-lasting
teapot.