My dream fish would definitely be an Achilles Tang. I've put a deposit down on an amazing Achilles, but unfortunately he was scared and jumped out of the stores display tank. After that happened, I decided to have them bring in another but unfortunately the one they brought me in, was extremely malnourished, refused to eat any form of food and wasted away within 2 weeks of being brought home.
I'll definitely some day try one again when i have the money to throw down on one again, but until then, I will simply observe their beauty in someone else's tank.