This mainly depends on what your looking to do with the drive.
Since your using CF I'm assuming the drive will be quite small so I would go for a distro which is light on disk space. You also said you wanted a Debian based system this brings two distros to mind Knoppix or DSL Both are descended from Debian (DSL is actualy a knoppix fork). They are both pretty fast as they have been desighned for live booting off CDs. I have used Knoppix as a desktop OS and although i did revert back to Slack I did enjoy the distro. I had DSL running on a USB stick and that worked very well.
The main diffrence is that Knoppix is desighned to fit on a CD so a install takes at least 80MB but DSL fits onto one of those little Bisness card CDs(50MB)
also consider Puppy linux (another live distro) or slackware (which can be made very small and fast during instalation)
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