BSA is awesome. It works great for me.
TheRealRazzy is correct about some sites with crap traffic. You will need to do the due diligence by using the search in BSA and then study specific sites based on keyword, then compare it to Alexa. I saw one site with 1/2M pageviews and 300K visitors/mo with 1M Alexa ranking, which is a sign of fake traffic.
Hope it helps.