The Best There Is Premium Pack contains the following alternate costumes.
Days of Future's Past
Patch
Brown
X-Force
Modern
Age of Apocalypse
Wolverine's Premium Pack also features plenty of in-game currency to spend, allowing you to pick up other heroes, costumes and consumables when Marvel Heroes launches.
Premium Packs now offer ongoing Closed Beta access to Marvel Heroes though the items in the Founders Pack are made available to you at launch.