G20 320d vs 330i - which is better for tuning?

Trying to decide between a G20 320d and 330i for my next car. I plan to tune it stage 1 at minimum.

320d: 190hp stock, ~240hp tuned, great fuel economy
330i: 258hp stock, ~300hp tuned, more fun but drinks more

I drive 30k km per year so fuel costs matter. But I also want something fun. What would you recommend?