I really don't think brand is too much of an issue. You are more interested in features, which most brands will have the same features. If my thinking is correct there are very few snorkel manufacturers, but many different brand names.
Features you should consider are, a dry or semi dry snorkel. The dry snorkel will pretty much seal up when submerged. The semi dry snorkel really is just a snorkel with a diverter to protect against water in conditions with some wave action.
The larger the diameter of tubing the more capacity it will have to deliver air, but most of that is the same across the brand spectrum.
Good Luck!