I use ON 100% Natural Vanilla, tastes pretty good and no artificial colors, flavors, or sweeteners. Usually I mix with water, sometimes with orange or sour cherry juice depending on the time of day, if I want some carbs to go with it.
I used to use a different brand can't remember what it was called until I noticed it had about 40% of my daily allowance of cholesterol in one serving, figured that was on the high side, some of them are pretty high though so may be something worth looking at on the label.