I like the monthly new coral and selection. as well as the swag... Being a teacher with a classroom tank the silver would likely be the option we would choose if we could.
Official Entry - i like that the silver level is under $100 and includes shipping. $20 each to your door for WWC frags is a steal! the higher level corals are probably amazing, but the silver level means virtually everyone can get in on the subscription fun.
also the fact that we can specify our aquarium size, skill level and types of corals we're interested in really lets us personalize this to exactly what we're into... i might just go sign up right now actually....