I have always held the belief a diesel works out more expensive over time, as it is expensive to service. So if you plan to keep the car for quite a few years you may end up paying more in the long run.
No evidence to back that up though.

In Portugal you pay extra road taxes on diesel cars, I think that is important, why is the government making you pay more? Probably to dis-incentivise people from buying diesel cars.

I would buy petrol over diesel any day, I have bought a few cars at auctions (repossessed cars), mostly dealers would be there, they did not TOUCH diesel cars. Any fault would cost them too much.

Until electric is more accessible we have no choice but to keep using petrol, I would have loved a leaf, but they are still very pricey here!