Fun Facts.
Hots and Dots (like corruption) gain benefit from the haste multiplier twice as it increases damage AND it reduces the global cooldown / cast time.
crit only benefits you once and in fact its effect is reduced by half in pvp.
you gain more %haste per rating than you do crit .
TLDR: For hots and dots 10 haste = a 8.6% DPS increase 10 Crit = 1.7% DPS increase
Disclaimer: the above figures assume that the class in question gains no passive benefit from either stat ( ele shamns , disc priest, and holy paladins are examples of some classes that do)