I am using a miller performance. Absolutely love it. I was using a cheap Hawk auto-darkening before the miller, and it was marginal. Not dark enough for me though, and there was no adjustability.
I guess I'm just stubborn or something, but I don't like auto-darkening helmets. I grew up with the older style, paper helmets. They run about $40 for a big lens mask and are rebuildable. I never liked the weight of the auto helmets.
I got one from Sears for like $20. No bells or whistles. My auto darkening lens is me flipping it down, lol. how can you work without bells and whistles?
auto darkening is great if you got a crap ton of tack welds to make. Otherwise, I just stick to the regular kind. I just hate it when they freak-out and start switching on and off in the middle of an important weld. I did try a couple of higher end miller models though and they seemed to work well.