I've had bad luck with a few brands of CF cards, usually the problems aren't immediately obvious but these cards are definitely unreliable and I would never use anything other than SanDisk CF cards now, which have worked perfectly for me every time, and I think I have probably prepared, formatted and installed Workbench on at least fifteen CF cards for about eight different Amigas over the years.
I think the perfect cards to get are either a 4GB or 8GB SanDisk Ultra II. Just patch scsi.device and use SFS if you use a 8GB card.