There may be some confusion here, so I'll clarify this first...
Hornet is a Yorktown Class Carrier, from here on out called Hornet 1. Essex and Yorktown II (and Franklin coming) are all Essex Class carriers, very different from Hornet.
Hornet has some issues, most notably the bow and lower hull. It's possible to do a 1941-42 Yorktown I or Enterprise, but you'll need to make some changes. Nautilus Models does a conversion set, but I saw one up close and personal the other day and it's not worth the $50+ they asking for it..
The Essex and Yorktown II kits are both very nice, but again, it depends on WHAT carrier and what time period you want to portray. You can do most of the early Essex Class from the Essex kit, but you'll want the YoOrktown kit to a mid-late war Essex Class. Franklin will be a late war version, so once that's out, you'll be able to do any version of the Essex Class from 1943-1945, and a few that remained unchanged into 1950s.
These are, of course, all short hulled Essexes. There's no plans to do a long hull that I know of. This gives you a total of 11 ships you can model.
Hope this helps, if you need any other advice, post up or drop me an email.
Regards,
Jeff Herne
Modelwarships.com