8" is usually considered good for beginners, but the bigger it is the more light it lets in so you can see deeper into space.
You won't
see the images of deep space through your eyepiece like you see them in the photos you take though, but I think you know.
Just buy a telescope that you will really love and doesn't frustrate you. You could also buy a small dob for the first few months to get better acquainted with astronomy and then sell it and buy a bigger and more sophisticated scope also suitable for astrophotography, or also keep the first one if you don't need the money.