I'd recommend both. But here's what I did last year (not that I recommend it...it's just what I did).
I just bought the 90D because I heard it's harder to learn on, but once you learn it, you can use it pretty much all the time. Plus the whole undilated thing. Also, I wasn't sure if I wanted a 78D or one of the other condensing lenses...I was overwhelmed with all the choices, especially since I'd never used one before. This gave me an opportunity to learn the 90D and hear my classmates' reviews on their 78's, superfields, digital this/that, etc. I plan to try some of theirs out (or an instructors...one seems to have one of everything, and he's willing to let us try them and compare)...then I'll put an order in with this year's 2nd year class.
Well, that's how it worked out. Really, I think I didn't want to spend anymore money after dropping some serious cash on BIO, FB kit, 20D, etc etc. 🙂