Bora
I'm very pleased with my Bora PD150. It gets around 47mpg (imperial) and on longer trips 53 or more mpg even when running over 70mph. Acceleration is pretty good too. I embarrased some half wit in a BMW 328i going up a steep hill recently. The torque is very impressive. Build quality seems good and other than a rattle from the fuse box I've had no problems.
If you are driving short trips though, under say 15 miles then there isn't much to choose between the diesel and the petrol. Mine takes around six miles to get up to operating temperature and fuel consumption is much higher until it warms up. If you're only driving around town on short trips a petrol is a better option in my view especially as petrol is significantly cheaper than diesel.
One of my friends has a Skoda Fabia RS with the PD130 engine and this goes like stink so is another option to consider.