I exclusively use the Sandisk Extreme III memory cards. When I first got into photography I had the 2GB vesrsions of this card and I have never experienced a single failure. I think it’s safe to say that most photographers pick one type of card and unless they experience any failures, most likely stick with that type/brand for a very long time. The thing that initially attracted me to these cards was that they are rated down to -25 degrees C. I have actually used these in far colder temperatures and as I said, so far so good. At the time the Extreme IV cards were not available and even though they are now, for me I dont think the download speed of UDMA technology is worth the price premium just yet.
These days I use the newer 30mb/s versions of the Extreme IIIs in my cameras. 4GB cards in my 1DMKIIN and 8GB cards in my 5DMKII. To download the cards I use the Sandisk Extreme USB2.0 card reader which I think is excellent value at only around $25. The tests performed on this site indicate that it is right up there with the fastest readers when combined with the Extreme cards. The other nice thing about the Sandisk cards is that it includes a copy of the VERY useful file rescue program RESCUEpro with each card. The program has saved me several times from accidental card formatting and has always succeeded in brining back my photos! It also works well on normal hard drives, not just the CF cards. This isn’t intended as any sort of comparison against other cards at all , i’m sure that other brands also have very reliable cards that can withstand similarly harsh conditions. But in my experience the Sandisk Extreme IIIs have been great in cold, damp or wet environments.