All depends on what you want the car to do really. Also how are you purchasing it? There are good offers on at the moment. If you have a scrapper then you can get shedloads of a 1.4 1, if not, then petrol for diesel may take your fancy?
Let us know what you are using the car for and we can advise better.
I have a seat Ibiza at the moment and looking to trade it in, I am looking to buy a diesel as I have a 80 mile commute to work and back so petrol not really an option, as far as the trade in goes car is a 05 reg so not a scapper.