Neither are bad products but they are very over priced for what they are. Cell tech is a nothing more then creatine and glucose. Nitro tech is a whey protein supplement. You could get the exact same thing for a lot less money by purchasing generic version of each. You are paying a lot of money for the muscle tech brand name and all the marketing behind cell tech and nitro tech.
When purchasing supplements the brand isn't particularly important. What matters is the ingredient list and supplement facts panel.
For a whey protein - you want to see nothing but that in the ingredients list. Whey protein, natural flavours, a natural calorie free sweetener like stevia and then maybe some salt, soy lechitin and cocoa powder. There are a lot of good products on the market. I personally use isolation from n2bm.com. A good whey isolate should be pretty much fat and carb free. Isolation has 26g protein, 1g carb, 0g fat per 30g scoop.
For a creatine supplement - get either a bulk creatine monohydrate powder or a capsulated creatine product like ancient strength from n2bm.com