The best directory script is esyndicat IMHO. They just have their latest version out which is superb. I'm uploading it as i type this post.
The Obvious answer will be PhpLD and for a bidding directory it will be PhpLB. The next time please also use the Search function
I agree eSyndicat is currently the best looking script out there however is more expensive than phpLinkDirectory which is the second best. On the other hand, most of the features built into eSyndicat will be extra/additional with phpLD.