Choosing CCD

Hi,

I'm an visual observer with some experience. But now, I'm planning to
start CCD astronomy. I've two telescopes:

· My portable telescope is a Vixen Newton of 8" and 800mm focal lenght
(f4) over a Losmandy GM8 mount.
· My fixed telescope is a Meade LX200 of 14" and 3556mm focal lenght
(f10) over a Losmandy Titan mount with Gemini.

I've to choose between a SBIG-ST7 and a SBIG-ST8 (with autoguiding)
cameras. I want to use it in all my telescopes, assuming I need a
focal reducer for LX200. Mainly, I use for photometry, astrometry,
comet imaging and asteroid occultations of stars.

Which is the best camera for my preferences?

I need experienced users advices.

Advanced thanks for your help.

Solstici