It depends on your goals, right?

If your goal is "maximize total happiness", then engineering blisshrimp is obviously the winning play. If your goal is "minimize total suffering", than the play is to engineer something that 1. experiences no suffering, 2. is delicious, and 3. outcompetes existing shrimp so we don't have to worry about their suffering anymore.

Ideally we'd engineer something that is in a state of perpetual bliss and wants to be eaten, not unlike the cows in Restaurant at the End of the Universe.