The Mango Peach-flavored Isopure from Nature's Best, but ONLY if you get a good batch and not one with the stinky whey. The batches with the good, odor-free whey are the best-tasting zero-carb protein powder in the industry, bar none.
I tend to prefer fruity to milky, but their cookies-n-creme is also pretty good and I haven't encountered the stinky whey issue with it.