Digital photo prints – What's best ?

Following on from a recent thread about printing digital shots, I decided to e-mail some of my files to a couple of online printing houses to see how they came out…

All shot on my Canon 10d and with no cropping, I sent the first one to http://www.fotopic.net and asked for a 10×8 print. It was a close up of a Boeing 747 taking off and they sent it to me with the nose slightly chopped off.

My question therefore is the 10×8 size the wrong aspect ratio for pictures taken on the 10d’s somewhat more widescreen(esque) format?

Next I sent a few files to http://www.colab.com who make you download their uploading software prior to sending them anything. I asked for A4 prints this time and they arrived containing all of the frame I shot, but with a thin white blank area at the top and bottom of the prints.

Any ideas as to which of the standard print sizes fits the 10d format the best would be appreciated.

Incidentally the quality of the prints from Colab was far superior to the other place.