I'd buy both cause they complement each other pretty well. You got Navy ops and USAF ops same time. If money is an issue, I'd wait till the hornet gets on sale and I'll pick it up for sure.
-Viper way easier to fly, easier to learn cause you'll be following the development. It is very fast so it is noob-friendly. The HOTAS is much better designed so you can do almost everything from your hands-on throttle and stick. Refueling is even easier for me.The viper is the new toy, everybody want it but there is not much to do right now so ppl will come back (Like I did) to the hornet while they finish it.
-Hornet is much more completed but is hard to learn. Feels much more responsive than the viper, and has mentioned before, hornet can fly low and slow. Carrier ops, that's a very good reason to pick the legacy hornet. You will have hundreds of hours to enjoy it and don't get bored.