Which FPGA, etc. is more better for digital video filtering?

Hello.
I’m a Moscow State University student. I study in Graphics and Media Lab (Video Group). We write a video filters (free filters are shared on
MSU Video Group / Video data filtering and compression)
. We need to write cores to FPGA programming, but we don’t know, which FPGA is more better for our work. Please, help us to do right choise (which development kit and FPGA we need to buy). Tell us, which parameters of FPGAs we should to see at first (for digital video filtering)
Thanks.