I'm going to go with the sand because it pisses me off the most. A one stroke penalty for going into the woods or into the water would probably be better to my game. That's how bad I am from the bunker.
The worse type of hazzards around here the alligators which often sun themselves on the banks of the lakes and ponds. They are much worse than the water and a wise man gives up his ball rather than retrieve it!
Water... 99.9% of the time, recovery is impossible. Once in a blue moon, you get one of those shots where it's just 1/2 submerged and you can actually hit it out, but not often... not to mention the fact that in the water, you lose the ball.
A bad hazard that wasn't on the list is poor course design. I played a course for the first time yesterday that had elevated greens on every hole. None of them tilted towards the fairway, so you had no view of the hole. We had no idea whether we had green to shoot to or not. Every hole had huge bunkers or water in front of the greens, so the ball had to carry onto every green. There were no options to bump and run the ball. Because the greens all fell to the back, shots hit high were difficult to spin back when the pin was in front. About half the holes had ridiculously tight driving areas.
The problem is, this was a public golf course. It took 5 hours to play 18 holes because everyone on the course was constantly in so much trouble they couldn't get around. I just didn't understand it.
Golf courses are of course designed to put you into trouble at times but I have played on courses where to drive straight over a marker post can put you in danger on the 2nd shot. Not maybe directly course design maybe but annoying nevertheless.
However, the worst hazard on any course surely has to be the mindset of the player.
in my opinion the worst hazard is the stuff that shouldnt be there. For example, In a tournament I played my ball got stuck in a BBQ. CAN SOMEONE PLEASE EXPLAIN WHAT A BBQ IS DOING OUT ON A GOLF COURSE!?