I vote A! What did you decide to do?

The wall gaps to the cupboard carcass could easily be filled with scribed strips - this would be standard for a new fitted unit anyway. Gaps to side of sink may be more of an issue as they could collect water, but I guess that's a standard size sink and you'd have a hard time finding one to fit perfectly, so again a scribing strip in a water resistant material could be the way to go.

I forgot that curved countertops are a possibility within the kitchen. Makes it look classy.

Hi Alice, that's a really good question - challenging dilemma with a strong limitation (no hacking!) but I believe workable. Would you consider making changes to the backsplash? Adding some strip lighting will help too. Given the pink checkered floor tiles cannot be changed, I'd favour going for very neutral and clean looking cabinetry - to reduce visual clutter and bring in some harmony. Regardless of colour of finish choice, I prefer cabinetry that's not see-through. How about natural wood finishes: All-white with wood countertops might work as well: I leave it to the professionals to give their advice!