Sibley Guide

I just got the Second Edition of the Sibley Guide to Birds. Although I prefer National Geographic's guide they are both very good. Here is a list of pros for each book that the other one lacks.

National Geographic:

• Better drawings with more accurate color
• Smaller size for easier use in field
• Subspecies taxonomic names are shown
• Range maps are better
• More rare bird species (just in case!)
• Special subspecies maps for a lot of birds

Sibley Guide:

• Easier to compare species
• More hybird and variant plumages
• More exotic birds
• Good tips for species comparison
• Checklist in back (although a lot of rare birds aren't included)

Other guides are good as well. There is the Peterson guide which is very informative. The Crossley guide uses many images from one species all on one page. I think that NG is the best choice but I do know people that like Sibley better, and they are both good guides.