I really liked Origins. The world and the stealth were amazing, even if the combat was terrible. I think Odessy and valhalla were quite crappy. Stealth were nowhere near as good, and oddesey looked a bit crappy to be fair. Pretty fun naval combat though.
Far Cry 3 and 4 were awesome. The main missions and the combat werent the greatest, but taking over outpost was a blast. Taking a outpost in fc4 were some of the best gameplay moments Ive had. The outpost were very well designed. Even hunting animals to upgrade you ammo bags was fun and done tounge in cheek. 5 rhinos to get a slightly bigger wallet, like you could only use the skin around the horn or something. I tried riding a helicopter and blast them with a grenade laucher, but that ruined the skin. So I rode an elefant and smashed them instead.
5 just seemed lazy, the whole outpost thing was crapp. You got sniper with silencer early and there was no penalty (like search patrols or mortar fire) for taking out a whole outpost with your sniper rifle. Same thing with fc6, and they added alot of unnecasary bloat like different ammo types and gear.