I was bought a paella pan for my birthday. It had a small label on it with only the brand name on, which I've since washed off. It is steel (I think), with rubberised handles and dozens of concentric dimples on the surface. I was wondering what these impressions were for and by extension, what makes a really good pan for making paella in?
I believe the dimples are for two reasons. One, they possibly help to make the pan, which should be fairly thin, more rigid. Secondly, they are a reminder of the time when these pans were hammered by hand - so, in a way, they make a factory-made pan seem more authentic.
The pan should be fairly thin, yet rigid, and conduct heat well. You don't want localised hot spots, but a strong, even heat.
The pan should probably not be too non-stick - you want to encourage the formation of socarrat - the slightly crusty layer at the base of a good paella.
The "how to cook" series in the Guardian are excellent for researching various recipes and deciding on an evidence-based amalgam - have a look at http://www.guardian.co.uk/lifeandstyle/2011/aug/18/how-to-cook-perfect-paella.