I'm not sure there is an objective "best" choice. I use SanDisk cards bought from a major supplier (to try and avoid forgeries). I have a mix of 2GB and 4GB III and IV series cards. They hold about 150 and 300 images, respectively, in 12-bit NEF lossless compressed format. The 2GB's feel a little small. I like the 4GB size. I would feel paranoid about significant image loss with larger cards. Not so much because the size is fragile per-se but mostly due to having 400, 500, or 600 images on one little card. Lots of eggs in one basket!
I have several Lexar UDMA 300x compact flash cards. I can't really compare them to any other brands because they're the only cards I've used. Any of the major brands ought to be fine unless you really push the limits of the buffer. Then speed and capacity might make a difference.
I chose Lexar over the other brands, notably San Disk, for no particular reason other than that Lexar was offering rebates at the time I made my purchase.
stuff: D300, AF-S 17-35 f/2.8, AF 35-70 f/2.8, AF-S 80-200 f/2.8, AI-S 50 f/1.8, AF 85 f/1.8 D
and: D70, AF-S DX 18-70 f/3.5-4.5, AF 70-300 ED f/4-5.6
For me it's the Sandisk Ultra II 2g, Extreme III 4 & 8g. I purchased my cards from reliable dealers and took advantage of rebates. I purchased the Ultra II's for use on my D200 (I still have the camera) and will also use them on my D300. On the D300 I can get about 100-125 pictures in RAW. I will get about 200-225 pictures on my Extreme III 4g.
I think the question as to what size depends on what type of shooting you do (frequent burst shots), the volume of shots in a given outing - say a day's shooting, the method used to download the pictures on to your computer, and how you file your photos. I am not a prolific shooter and in a typical days outing I might shoot about 200-300 photos and do not typically use burst shots. I use a card reader to download my photos which does take a bit of time to download. Under these circumstances the Ultra II 2g works adequately although the Extreme III 4g is probably a better overall combination.
The question as to "all your eggs in one basket" by use of a large gig card vs. "spread you eggs in many baskets" by using smaller gig cards will prompt endless dabate with each side presenting valid arguments. I think each user has do decide for himself/herself which side of the argument to fall on so I am not going there.
Welcome to Nikonians! Thank you for your support. I use Sandisk 4 Extreme III and 8 GB Extreme IV 45MB/sec cards in my D300. As stated above, buy your cards from a reputable dealer and you should have no problems. Good Luck and Enjoy your Nikons!
I have San Disk Extreme IIIs (4GB & 8GB), Lexar Pros (300x/45mb/sec) 8GB, and just got a San Disk Extreme 8GB (60mb/sec) to try.
I personally have been happiest overall with the Lexar cards. The Extreme IIIs are ok, but I have had the most failures with these cards - plus the faster write speed on the 300x Lexar Pros is an advantage for me.
For whatever it's worth (or not!) I typically shoot equestrian sports in RAW (NEF) + fine jpg.