Best telescope for value, future upgrades, and amateur-to-advanced growth?

Hey everyone,

I used to have a 6″ dob, but I no longer do and I’m looking for a replacement.
Since it’s not my first telescope and I don’t have a fixed budget, the buyer’s guide didn’t give the answers I was looking for.

I’m really interested in best value for money and upgradability for the future, no matter the price, not just “beginner‑friendly” models. I’d also love to eventually mount an amateur camera onto the eyepiece.

Questions I have:

1. What telescope or package would you consider the best in terms of value and future upgradability?
2. What should I get at minimum so that upgrading optics later is worthwhile and I’m not forced to replace the whole system?
3. At what aperture do the benefits start to become marginal?
4. In terms of value and upgradability, how do apo refractors compare to Newtonian reflectors?
5. Is it feasible to use the same setup for basic astrophotography (pictures that look roughly like what the human eye sees, rather than long-exposure deep-sky images) in the future?

Any personal experience, comparisons, or recommendations would be much appreciated!