in my experience, buying lenses from the company that makes your camera will always produce better results. visually compare a sigma to a canon or nikon through the camera and you'll see the difference right away. not only are they made to a higher quality in most cases, they are more compatible with the cameras. All lenses not made by the manufacturer have to be reverse engineered and have less tolerances for precision. So if you want the best quality lens, buy it from the company that made your camera.
Now as for types of lenses, i prefer to get macro zooms because they allow you to say far from the subject to image it. This reduces the stress on the subject and (in the case of venomous or poisonous animals) keeps you safer. In the case of aquariums, it gets a little buffer space from the water and the camera. Be sure to never get any salt water on your camera gear, it can rust it and degrade the optics substantially, very quickly.