Hardest: Adventures of B&R on Sega Genesis. Completely impossible difficulty.
Worst is probably Dark Tomorrow since it was unfinished and not even ported to ps2.
Returns and Forever on Genesis were impossible and frustrating.

Arkham Asylum is the finest game imo, City refined the gameplay but had a lesser story, Origins was a cheap reskin and Knight was a massive disappointment.

I grew up playing every Batman and Star Wars game I could get my hands on without realizing they are two of the worst game licensed properties ever.