Yep, as mentioned, copper and sweet iron are the best choices. I don't know about sweet iron being more of a western material, I am sure that you could find a snaffle or something in it, I have never looked. Probably the best would be a sweet iron with copper inlays, that's what my curb bit is and my horses seem to really enjoy it.
If you are looking for a snaffle and can't find anything at the EA, here is a site with sweet iron snaffles. http://www.horsefriendly.com/store/s...ffle_bits.html