well, taking the view very few contracts are ever taken to delivery, id say goodnight nymex wti. along with the guys i work with, we've rolled out of our open postions in america to roll them into wti ice if only to save margining costs.
i feel ACCESS sucks. and, unfortunately, whilst ICE is far from perfect and actually takes the **** with its clearing charges, it is the only WTI alternative at the moment which is cheaper than me sending orders into brokers in the pits......
also, its pretty damned obvious bp, shell and several of the big banks are backing the ice wti and i have no hesitation in predicting another dtb vs liffe bund scenario developing with the winner being ice in under a year.