It is absolute nonsense to say that a newer type aircraft is safer. On the contrary, old well proven designs (PA28, C172) are more likely to have had all their faults ironed out, and even they from time to time have AD's sprung.
Diesel engines (the only ones available currently) are totaly unproven. Thielert just went bust after providing the bulk of the diesel engines, and all those had very limited life and many failures.
I would say get the best training possible, get the best maintenance possible on a well seasoned type aircraft which is well within your capability and dont try to get for the most modern equipment but for the most proven one.
It is all about prudence.
Finally fly as much as you can and even then get yourself tested by an instructor AT LEAST once a year