You guys must be lucky or have really clean water.  I can't even use brass float valves here.  They only last about 5 years before the seat corrodes so bad they won't shut off.  Plastic or stainless and plastic is a lot cheaper.  I'd look into pure core plastic, don't use black plastic!  Thats a band aid just looking to get ripped off.  Pure core and shark bite fittings.  Fastest plumbing you will ever do and it lasts for ever and I've never had a fitting that leaked.  There is nothing wrong with good PVC and the high end gray colored glue either.  Metal plumbing of any kind other than stainless is a joke here. YMMV