Personally love mapei. Used to be a bal man but I feel as if bal grout really getting difficult to use, then there is the price.
Mapei- great price, sets really quick. Tub or powder. Grout dries fast aswell. Ideal for polishing shortly after grouting.
Price, drying time and quality. Mapei is a straight winner for me.
I have seen a lot of guys raving about tile master, unfortunately I have only used it once as no one near me stocks it. So I can't give an honest opinion or feedback on it. :-(