That looks like a somewhat biased graph on the Wiki. The Standard diesel is rated at 138hp max like the petrol. The wiki graph shows 153 (@ 10% more !). Are all standard diesels producing this much extra power ?
Petrol vs Diesel - Civinfo Wiki
The other downside with diesels is that once they get up to higher mileages you are more likely to have some major engine repair bills. For example when things like Turbos, injectors and high pressure fuel pumps expire (which is not unusual on modern diesels).
I do think the Honda Diesel is a particularly good engine - fantastically torquey and smooth. The Diesel is closer to type R price both new and second hand.
Good advice from DerChef - try the cars and see which you like best. Some prefer Diesels, some prefer petrol.