Because I had a cracked version of Waves 5 I was using before. The earlier stuff is not compatible with 64bit for the most part. I'm glad in a way though - I don't really want to use cracked stuff anymore, and not using waves is forcing me to be more resourceful about which plugins I use.
The BC analyst is 'the best' one I've tried because it's free and I can see what is going on with it. I prefered the Waves one, but it's not unworkable.