My preferred format, from Marvel, is the Regular Edition Hardcover Masterwork. I generally buy books from the "Marvel Age" era, which means I'll buy books in the MPE Classic and Omnibus format for material that isn't likely to be printed in Masterworks format in the forseable future. While I like the MPE format, I find the Omnibus format a bit cumbersome. Overall, I prefer hardcover collections, but sometimes companies don't provide a choice and you've gotta go the trade.