I'm sure this subject has been discussed but I am curious. For the most part, the "memory card wars" have "ended" with two major players. SDHC and CompactFlash.
Now, if memory serves, compactflash, was for a while, faster and had larger capacities available than SDHC. But I've noticed lately that SDHC cards are just as fast, have almost a high as memory capacity, for the most part. I mean CompactFlash Extreme Pro has 256GB cards and SDHC has 128GB and 64GB cards available. I would imagine that 64GB cards are about as high as most people carry around, unless you are a professional and you need a larger card.
My wife's Nikon D7000 and D7100 have dual SDHC slots. Pretty sweet I think, but my poor 7D has 1 compactflash card available. This is ONE feature I would like to see in Canon bodies. The 5D3 dual slots don't count as they are mixed AND the SDHC slot doesn't transfer as fast as the CF slot.
Canon and Nikon have both not standardized memory card usage. In saying that, both Canon and Nikon use CompactFlash cards on the higher end bodies and SDHC on the "lesser" bodies.
Now that SDHC cards are faster and have higher capacities is there an advantage anymore? I know that a lot of people don't like putting all of their photos on large cards just in case there is a failure. I think 32GB/64GB is about maximum I would go.
Not that I really care, BUT compactflash cards ARE almost twice as much as equivalent SDHC cards. I bought a 32GB extreme pro card for my 7D and it was $140.00 while I spent that much buying TWO SDHC 32GB extreme pro cards for my wife's D7100. Not to mention that now she has 64GB if shooting room vs my 32GB on her D7100 and 2 64GB extreme SDHC cards in her D7000!