My iron requirements are pretty simple. I want steam and a stainless steel sole plate. Since most irons have the first, all I have to do is make sure it also has the the second. Many of the really cheap (around $15-$20) irons have a non-stick coating. I have zero interest in one of those. The last non-stick iron didn't have a full coating by the time I was done with it. I had worn it off around the edges. Since then I always get the stainless steel sole plate.
I also really like the Black & Decker irons. They always hold up to how I use an iron, which is to turn it on and leave it on pretty much all day. Granted, the auto-shut-off will engage, but they heat quickly and I can get back to work. The burst of steam is nice, too.