Doesn't really matter what brand you get, any 50W+ iron will do just fine, however it's VERY important that you get an iron with a chisel tip, because you need more surface area to heat up the wire properly... there are many brands of tips out there too. I'm using a cheapo $15 iron (50W) that I got from RadioShack about 8 years ago, and the tip that came with it was junk, I simply replaced it with a TENMA chisel tip and that tip has been doing great for the past 3+ years! I solder up to 10AWG no sweat.

Before I found the TENMA tip, I used to file the original tips, but no longer do that, here's a sample of the iron using 10AWG to see what to expect: