I have the 590A1 Retrograde after owning the 590 version and I would say both have a quality build for the price and if you have the funds to get what you desire then go for it. If you do not, then either wait until you do or settle for something that you can afford. No matter what you buy, there is always a better version out there. Get the best that fit your income and requirements.
There is a concept called the "Boots Theory". In essence, it says "A man who could afford fifty dollars had a pair of boots that'd still be keeping his feet dry in ten years' time, while a poor man who could only afford cheap boots would have spent a hundred dollars on boots in the same time and would still have wet feet". Kind of like the wife that buys 10 pairs of "cute" shoes that wear out in six months after being worn twice while the guy still has the same pair of dress shoes since high school. Which was the best buy? It depends on what your priorities are and how much you are able to spend.
If you are asking us to spend your money, I would say buy the Mossberg 590 Retrograde and go have fun. It sounds like it fits all of you criteria. There are tons of aftermarket bits and pieces and as someone said above, most are interchangeable within the 500 family. Hickok45 has some good videos on several shotguns that may sway your opinion as well.
And best of all, the 590 Retrograde has a bayonet lug because you know, you "need" one......
