I use the aluminum. But I know some people have a problem with it so...
Using a pasta pot with the strainer insert is a good alternative.
This is pretty coold but note that the legs on the bottom of the insert aren't that long so not a lot of water in the bottom...
I saw this one in store and wanted to take it home. My wife talked some sence into me. Its HUGE.
This one is nice as you use your own pots and just insert. I have used this one before. This one is very large but you can go elsewhere on the site and find smaller. I like the large as it lists its maximum size. You could always collapse it a bit for a smaller pot.
This is the steamer I use but it is aluminum.