Back, but it's often reserved for RAP, but even if it is, the second or even third to last row are just as good.
The front is good, but I allways found on the front that by the time the train was released from either of the lift hills you were almost already at the bottom, you got a nice view, but the front row is not in the remotest bit forceful.
Quiet often the batcher will tell you where to go, but if you ask nice they'll let you go to the back or wait, or you could just do what I see a lot of people do and ignore the batcher and go where they want, the poor batcher has enough of a problem trying to stop too many people from entering the platform let alone controlling people once they are on it, so invariably they'll shout once or twice at you and if you still ignore them, just give up, as one once put it to me, it's like trying to herd cats. Never done it myself, we mostly go on via RAP, but doing that gives you a unique view as to how the GP behave.