Over Seward. Prince William Sound is a bit more scenic IMO, but more importantly, it’s protected waters. I’ve had family members get seasick on the Kenai Fjords tour. Also, you get to drive through the tunnel to Whittier which is kind of cool.

Whittier isn’t much to write home about. I wouldn’t spend much time there. I would still drive down to Seward, if nothing else for the Sea Life center. Nice hands on displays there. The side trip to Exit glacier is worth the short drive in my experience, but I haven’t been there in 7-8 years so I don’t know how much it’s receded.