I've had all three in my town. Zucker moved out long ago, due to me not playing for about a week or two. Got on, and his house was gone :c Octavian did the same thing, and it was pretty recent, a few days ago. Marina has been in my town the longest, and she's the most adorable thing on the planet. But Octavian is my absolute favorite octopus. I enjoy his cranky face.
They are all so adorable, but I'm going to have to go with Octavian. Something about a grumpy, bitter personality bottled up in such a cute little body really gets me.
I voted Marina, but though I have her in my town, I like her less than I thought I would. I'm guessing it's because she's a Normal. I might have liked her better if she was Uchi or Snooty or something.