I have used Biobizz Allmix in the past and had some good results.. but this time I'm giving Plagron Royalty Mix a go (with some perlite i added of my own)..
Will let u know how i get on..
I recommend Pro-Mix Seed and Clone. Availible at Agway and other garden stores this mix is comprised mostly of peat, which allows for good root arreation and penetration. The nice part is they have already added the lime for you (to combat pH fluctuation). Just add some perlite, vermiculite, and a dry fertilizer (I like bat guano or Rainbow Mix) and you are good to grow.