Require such high reliability, use the best brand, Germany Rexroth or American Vickers can be. Suction and closure 100 times is not a problem, many valves can do. Hydraulic oil must be strictly controlled oil temperature and cleanliness to prevent the valve spool from jamming.
For this highly reliable system, I would recommend a shut-off valve type directional valve, also known as a seat valve (set vavle), which is a bit more reliable than a spool valve (spool vavle), and the spool is less likely to jam.