I've created a thread asking if directories are still a good business or not and replies really made me think there is still plenty of room for a good quality directory.

Now I need your suggestions regarding the niche of the directory. Should I go with general Directory or go for a specific niche?

I'm now seriously planning to develop a quality directory (not the usual crap) and am ready to put in good effort.

I'd love to see some good suggestions and advices from Experienced guys