I've used many brands over the years, and these are my top 5 suggestions as of right now. And besides...my name is Whey Man. So I most know my whey's pretty well, eh?
1) Biotest Grow! Whey
* Yeah I know...the typical response. Bun one can't deny the high quality and excellent taste Biotest's whey provide.
2) Champion Nutrition Pure Whey
* This stuff is great and also of high quality. Some flavors you'll want to avoid (vanilla in particular), but the rest are pretty darn good. If you love dark, rich tasting chocolate...Champion's Chocolate is definitely the way to go. I'd refer to it as "gourmet" chocolate. Champion also makes MRP's called "Low Carb Ultra Met" that are perhaps the best tasting whey's I've ever had in my life. Brownie Fudge and Vanilla Cream honestly taste exactly like they sound.
* I basically started out with these guys. If you like thin shakes (as opposed to thick), ON might be the whey to go (my clever play of words = amazing). One flavor I've seen no one other than ON make is Chocolate Mint. Good stuff. They also make a great tropical flavor that's very tart (it acutually used to be more tart, but they must have changed something).
4) Nature's Best Zero Carb Isopure (or) Syntrax Naturals for fast acting whey's
* The reason I put this one on here is if you make your own PWO shake cocktails and are in need of a fast acting whey, this would be a great option. Granted, the only flavors I've had are vanilla and Pineapple Orange Banana. The the P,O,B was enough reason to include this. Syntrax also makes an assortment of fruity, yummy tasting flavors that taste absolutely superb in a PWO shake combined with maltodextrin and dextrose
5) Labrada's Lean Body RTD
* I wanted to throw in an RTD for my last suggestion. You'll find that of all the RTD's out there today, this one is above and beyond the best. High quality with great taste. Great "emergency" option. Also gives you 9 grams of healthy fats.