LOX is definitely some bad stuff if it touches your skin. When I would fill the lox converters on the C-141, it would purge and go into the drip pan. Then I would find the closest insect and drop it in the boiling lox. It was freeze instantly.
The hydrazine is most certainly nasty!!!! An aircraft where I was deployed at (can't say which one) had that stuff. They say it can kill you with a minimum amount of exposure.
One last bad fluid that I can think of is Skydral (hydraulic fluid). That stuff can do some damage. I've heard of people that have used it for paint stripper with no problems. They use it on the other aircraft that we have here, not the one that I work on.