I use Beatport personally because I love the interface. The site is fast and easy to use. Their audio player which is embeded makes for fast purchases. Navigating between artist, labels and style is seamless and helps to find hidden gems. Unfortunately i don't really like the length of their mp3 samples.

I am starting with trackitdown.net as it was suggested in another thread. They seem to have better selection of hard techno and tribal tech.

Another thing that really annoys me with Beatport is that they have Hard Techno in a sub genre with Happy Hardcore....Sigh. It takes a really long time to go through the new releases to find hard tech.