Which Protein Powders are the best to use while trying to lose weight and increase your muscle? Whey, Casein? What brand? How much? etc. I do strength training four times a week, as well as cardio. I'd appreciate anyone knowledgeable in the protein powder fields answer.
I currently am using promasil, it's zero carbs and sugar, but only 20g's of protein. It's not nearly enough.

Go with whey protein for after your workout, this is fast absorbing protein and is crucial after a workout. It will help with your recovery.

Casein, which is slow release protein and is usually taken before bed so your muscles are provided with protein during sleep.

If your concern about protein content, then your best bet would be whey protein isolate, this is much more expensive than normal whey protein. The main difference is that whey protein isolate is processed further in the manufacturing of whey protein. The end result is a more pure protein, with much lower levels of lactose and fat. In fact, over 90% of whey protein isolate, by weight,is protein.

If you live in the US go with Optimum Nutrition they are very good brand. They are comparatively cheaper when compared to other major protein brands. AST VP2 is also a good brand (whey isolate) - quite expensive though. These are only ones that I've used when I lived in the US.

However, if you are in the UK, go with myprotein.com, they make good products and are cheaper when compared to other brands. I've been using them for a year now.

So should I go with both a Whey and a Casein? Whey for after workouts and Casein before sleep?

For a while I was drinking the whey protein just to add more protein to my diet when I wasn't getting enough. I don't know much about the others. :)