Neither nitrix or cell mass are bad products per say but they are really expensive for what they are. Nitrix is an amino acid supplement. Cell mass is a post workout creatine and carb powder. They aren't anything special. They just have really good marketing and cool sounding names.
Creatine is creatine. Don't waste your money on some heavily marketed creatine supplement that is going to cost 10x more but provide no additional benefits. Either get a bulk creatine monohydrate powder or a capsulated creatine supplement like ancient strength from n2bm.com.
I would stack the creatine with a good quality whey protein powder. A good quality protein powder will contain all the amino acids needed to build and repair muscle.
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.