While you may have already made your choice I add to the discussion "KOBELT",Canadian, high quality manufacturer of marine
and other industrial hydraulic and other systems. My own boat, Outremer
55L, 1997,was originally built with Vetus steering equipment
described by others in this Thread. In my experience the Vetus cylinders developed leaks
and sometimes it was difficult to get replacements
as Vetus supplies in the US over the past years has been difficult at best. It has been much better recently.
That said, I replaced the entire system with Kobelt variable steering
pump, sailboat lock valve, and cylinders, Also replaced all valves and all "old" copper lines with high pressure "plastic" hydraulic lines and fittings. No hiccups in 6 years.
The Sailboat Lock Valve is an interesting piece of equipment
. Take a look at their website.
Stuart, Ma Bete