I use Pure Whey. I have vanilla and chocolate right now. I searched long and hard for a chocolate that didn't taste bitter to me.
One thing to try is protein pudding. Jello sugar-free, fat-free powder, skim milk, and protein powder (I use 2 scoops). I mix it up and leave it in the fridge to set, it keeps for about 3 days. Try different combinations (lemon pudding and chocolate powder, chocolate pudding, vanilla powder, and orange extract, chocolate fudge pudding, chocolate powder, peppermint extract).
I use skim milk, frozen berries, cottage cheese, water, peanut butter, pudding powder, Greens powder, plain yogurt...all sorts of things in my shakes. Just play around and find a favorite!