We refinished our deck (Cedar) this summer. PIA. But its done. We did a ton of research and found the Sikkens Cetol SRD Semi-transparent to be highly recommended. One comment...the "SRD Semi-transparent" was much more opaque than the "SRD". We're very happy with the results...I bet the Cetol SRD Semi-trans would look great on a fence. Dunno is Sikkens has a different product they'd recommend for fences, that might work better.
Also, in my research and asking around locally, water based finishes were not recommended for durability reasons. That being said, I'm in South Dakota and we get pretty brutal temp swings (100+ in the summer, and -20 in the winter).
Edit - a pressure washer with siphon tube and cleaning solution is your friend. But turn the pressure WAY down...we found that it didn't take much more than 500 PSI to clean. The first go-around was with closer to 2000 PSI and lets just say we learned a lesson with that...