Both engines have there pros and cons.
D-series are MUCH cheaper to build, and can have a good power range(i've heard up to 300hp, turbo, of course).
B-series engines are more expensive, but are fast out the box, and can reach an insanely high amound of hp. Plus, they have a plethora of aftermarket parts to work with. Some d-series engines (like the zc) are gonna be harder to find aftermarket parts for.