I'm doing some work on a domestic water system, mostly 15 or 22mm copper pipe with compression fittings.
The work includes replacing various stop-cocks and drain valves some of which are probably 30 or more years old. Some are jammed solid, some turn easily and some turn eventually after squirting with oil and waggling back and forwards for a while.
Most of them rely on brass to brass contact, maybe with a fiber washer, and some gland packing to maintain a seal around the shaft.
I need to replace all these items, if my main criteria is working life expectancy, what should I replace these with? More or less the same thing? Or new ball valves with polished steel ball in a nylon housing? Bearing in mind that whatever I use is only likely to be turned on average, once every few years?