I generally use the Optimum Nutrition Pro Complex, chocolate flavor. I think it tastes pretty good. I had the guy at GNC just talk me into the GNC Amplified Wheybolic Extreme 60 - chocolate. I think it tastes great but I am disappointed at how it dissolves. I haven't found anything yet which dissolves like ON.
The thing about tuna fish is you should limit it in your diet because of the mercury. Study: Mercury in canned tuna high - News - ReviewJournal.com
Edit: Oh, I neglected to mention I still eat tuna fish ~twice a week.