I have seen both superb and very poor optics come from the same manufacturer in a month's time. I have found that a lot of good equipment goes unused because of the difficulty involved in setup and use. That typically leaves refractors for planetary work and reflectors for deep-sky, but catadioptrics can do both fairly well. Try them all at a star party if you can, just to get a sense of the different systems available. Let us first define the two.
Altaz mounts are like old camera tripod mounts.
Motion around the right ascension axis is about a line pointing to the north celestial pole. This allows the scope to follow a star by moving only one axis, since all stars revolve around the celestial poles. The declination motion adjusts the scopes position north or south of the celestial equator, an imaginary extension of the Earth's own equator.