I bought the TI-30XB multiview. It's AMAZING. It may not have as many of the functions as the Casio, but I think it's simplicity is what makes it so amazing. It has everything you need for the sciences, and it's not so complicated; you don't have to go through so many secondary functions to get what you need.
Personally, as a TI-Nspire user, the variables and STO-> (store) buttons are incredibly useful especially when you are dealing with so many different values. If you use the Nspire, I especially recommend it because it will be very familiar. The other scientifics are just unnecessarily complex in my opinion. ALSO...it's crazy thin unlike the Casio. (the sharp is pretty thin as well)
p.s. I really hate calculators as a maths person...so this is glowing praise from me.