Please vote and explain why you choose that aquarium.
I voted for Monterey because it is the single most un-compromised, mission-focused organization in the zoo/aquarium world. No glitzy theme-park "food courts" and cheesy lowest-common-denominator graphics (ala Georgia), no large marine mammals in (relatively) small pools (Shedd, Georgia, Baltimore), 100% fantastic exhibits, excellent use of technology for interpretation, great food and commitment to sustainable seafood, nationally-recognized conservation and education programs (Seafood Watch), beautiful integration with its setting (the Bay and the Wharf) and the single most spiritually-inspiring exhibit I've ever seen in an aquarium, even at 26+ years old: the Kelp Forest.
Shedd and NAIB are uniformly excellent, and Georgia unquestionably has a number of spectacular highlights, but for pure institutional quality (exhibits, programs, conservation impact, architecture, communications, people) Monterey is number 1.
I've visited all 5 of the aquariums in the past 2 years, and while I feel that they are all excellent my order would go: Shedd, Georgia, Monterey Bay, Baltimore and Tennessee. The 6 million gallon whale shark tank at Georgia is the single best aquarium exhibit in America, but in terms of species, exhibits and overall presentation my vote goes to Shedd.