The two main things that determine what skate to get are weight and skating ability. Assuming you are an adult, your feet aren't growing and your weight is fairly stable. so I would look at a skate that will work for you as your skating improves. (For a child, get what works now, the child's feet will grow and they will soon need new skates which can be upgraded to their ability level at that time). That said, don't get a skate too advanced either, it will be too stiff. Boots that are too stiff or too soft for your weight and skating ability both lead to foot problems.
As for brands, the various brands differ in terms of the last (shape of the sole) they use. Some may be narrower in the heel vs forefoot or the other way arround.
As other posters have said, try to work with a fitter locally. They will look at your feet, inquire about your skating level, check you fit in the boot and provide invaluable guidance in making your selection. If there is no fitter in your area, a trip to the nearest one is worth it, or find out which coaches in your area have experience in fitting and work with them. Beware a coach who says "I want all my skaters in xyz brand," unless of course all their skaters have identical feet. : )