Yeah, the protein creator is cool. A little daunting at first but you can get the exact formula you want.
Actually, I had a personal favorite and used it as the base of BIG BLAST. Ion exchanged whey with plasma serum , milcellar casien and whole egg. That, to me, is the best of all worlds in regard to protein. Keep in mind, the added fats, creatine, hydrolyed syrup and NO2 makes it a bulking drink.
For a lean formula I think any high grade protein with no sugar will work. I like mixing a slow and fast absorbing formula. All the wheys are fast and all the casiens are slow. Also check out ZIP and DEFINITION -- 2 non stim products that will help in the leaning process.
All in all, just have fun with it. You really can't go wrong with any of the top grade proteins and the site lists the BA of all of the individual powders.