I run a Paramount MyT with TheSkyX and NINA. I think it is an easy setup, but I guess it is hard to judge that from someone else's perspective. For a frame of reference I am a retired engineer so I am comfortable with teaching myself how to best use new pieces of equipment and software. In my setup TheSkyX runs as the planetarium software and connects via an ASCOM driver to NINA. NINA provides the hardware connections, plate solving, and sequencing to allow for unattended imaging throughout the night. Of course, you can do a number of similar things with just TheSkyX itself, minus the sophisticated and flexible image sequencing. As stated above, running a Paramount is going to be greatly facilitated by having TheSkyX, although perhaps the ASCOM driver can be used by itself and for no cost? I do not know as I have had TheSkyX as part of my original MyT purchase back in 2015. Running a Paramount without TheSkyX somewhere in the chain though is the opposite of a plug and play endeavor though I expect, assuming it can be done. On the other hand, there are lots of cool features of TheSkyX that enhance the pointing and guiding of mounts that use it, so I would not consider running a Paramount mount without it in any case.
I can state though that a used MX+, unless it has been abused in some way, should be an excellent mount that would be able to provide top level pointing and tracking for years to come. My MyT is 9 years old and has been wonderful for me.
The reality of this hobby is that it is still an endeavor that requires one to be able to integrate different pieces of software and hardware often from different manufacturers to get the best results. You need to be patient and willing to learn what works and what doesn't,although you can greatly benefit from an active community of users willing to share their expertise and experience. You are taking the right step here by inquiring here before just buying some gear to find out it doesn't work the way you thought after the fact.
ZWO has some excellent products, and seems to be one of the companies that is innovating quite aggressively in the astrophotography space, but they are definitely looking to keep the supported hardware and software in the ZWO ecosystem. So I would think an ASI Air is going to pair more completely with an AM3 or AM5 for instance. In any case though I think being ready to dive in and learn new things instead of looking for an immediate plug and play solution is going to be beneficial the farther you decide to delve into the hobby of astrophotography. In my experience I have had to treat improved capabilities and competency in astrophotography as a journey and not a destination.
ML