Hi, I don't think you can go too wrong with either choice to be honest... but my pick is the petrol.
I have had diesel (Peugeot 508GT) before my MD Titanium Petrol, and I enjoyed the extra range you get from the fuel tank and also the no-fuss engine torque and less gear changing going on too. I did used to have to keep a box of silicon gloves in the boot for when it came to refuel - as the diesel pump handle is always left covered in an oily finish and smell that doesn't go away from your hands (or feet if you stand in it). Petrol pump handles don't suffer from this problem. Big issue with launching into traffic on a roundabout/junction - the turbo diesel is slow to initially get going, and those first few seconds can be a bit nerve racking if the gap your aiming for is closing fast and you've already launched for it.
Petrol has more RPM obviously, and more gear shifting going on too. I no longer sound like a taxi when picking up dinner from the drive-thru! I don't have the low down surge of power, but instead have way more power and RPM - so I don't run out of breath when doing an overtake for example. Diesel runs up the hills nicely, but you need plenty of room for an overtake - in my petrol I can do both (just need to go down a gear or two for the hill though). Neck snapping launch from standstill should you be aiming for a gap in the traffic too.
Just to continue with my personal opinion, the $$ you save on diesel fuel costs is spent (and more) on the extra diesel purchase price and extra diesel servicing costs too... so unless you are going to do 400,000km - the running cost maths should prove that petrol is better in the long and short run.
It is also my personal opinion that diesel has reached the extent of its development, and I believe it has been proven that diesel is now falling out of favour as a car engine - European diesel sales continue to slide vs petrol models. Concerns over the dirtier emissions etc haven't helped too. The modern turbo diesel engines are much fussier on the types of fuel they can run with too - whereas a decade ago they could run on a very wide range of lesser quality fuels.
I enjoyed experiencing the modern turbo diesel recently in the Peugeot 508GT- but am very pleased to now run a Titanium MD petrol instead.
Everyone will have their own opinion, and as I said before - I don't think there is a right or wrong answer to this one... good luck!
