Ive got a 16v and my mate has an 8v, we tried an experiment and my 16v was quicker than his wherever in the rev range, everyone says the 8v's are more torquey low down or whatever but its one of them urban myths, however im now selling my 16v to buy an 8v as it works out more economical for me to run at the minute.
Basically you should test drive as many as you can with a variety of different engines and see what you prefer and then weigh up the cost of running it