Not really a clear cut answer, as all types have deadly siren-like traps. HPs are the obvious choice because of bad visibility, but a lot of HP tornadoes form on the FF, so to view these you really need to be out ahead of the storm......who wants to get in a blinding rainy cage when you can see the FF clearly out ahead of the storm? HP structure fans are of course well back of the dangers (to see the entire storm), so HPs aren't neccesarily the most dangerous bar-none.
Classics are dangerous in that their perfect balance and tornado-prone nature lure chasers in close for the action.....leaving not a lot of room for mistakes or escapes. Cyclic storms of the classic persuasion are particularly dangerous, because of the aformentioned reason: being drawn in close sometimes puts a chaser right below the next cycle/tornado, while at the same time, mesmerizing the chaser away from the danger area above, as it dances the rope phase of the old tornado a mile or two west.
LPs are probably the most stealthy, as their pure beauty echos the cry "look at me, I'm beautiful, I couldn't possibly harm you......" And then you've got a knot on your head the size of a walnut from the stray golfball (or even worse - baseball) that snuck out of the updraft and right onto you. Even if you yourself survive the impact, your windshield may not, as the stones are falling more and more as you frantically scramble to get your three tripods, twelve cameras, and two video cameras (one for timelapse, one for close-ups) back into your SUV and on down the road.
I don't know that I'd call any one type of storm the "most dangerous" to chase; perhaps the "most difficult" (HP wins!!) All supercells are as dangerous as the chaser chooses to make them. As is, they are just different degrees of difficult.
