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Welcome Pat
The replies above talk about exposure time etc. This is only relevant for taking photos through the scope. Visual is completely different.
For visual then the light gathering ability of the scope is all important. ie aperture. A 300mm reflector will collect the same amount of light as a 300mm refractor (negating the loss from the secondary mirror in the reflector)
A 300mm reflector will cost you under A$1000. A 300mm refractor would be somewhere near A$20000.
The refractor will have better contrast and slightly brighter image because of no secondary mirror but will cost 20x more and weight 3 times as much.
Essentially to see deep sky objects(with the exception of the few bright widefield objects) you need a decent light collecting ability ~200mm or better. Refractors of this size are prohibitavely expensive so most people opt for reflectors.
The focal length is not terribly important visually because you vary the magnification of the image by changing the eyepiece. However short focal length eyepieces are not as easy to use as the longer ones.
So to see deep sky objects (or planets) that are small and need a bit of magnification, using a longer focal length scope (~1800mm or longer) is easier with a 10mm eyepiece than using a 900mm scope with a 5mm eyepiece.
Bright widefield objects can be seen with a short focal length scope of any design but there are not that many of these to see.
Hopefully this helps.
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