I must say that I really enjoy the upgrade from MSFS-X to X-Plane 11. I use the simulator for practicing the maneuvers that my CFI covers on each lesson, plus I use it to get the "feel" for the other airports we visit during the training sessions.
I also use MSFS 2020 and FlightGear 2020. This is where I will start my comparisons.
X-Plane 11 excels in having a steam-gauge C-172 stock. The actual flight characteristics in the modeling (physics) are very, very close to the older C-172H models in use at the flight school I am using. I just have to mentally convert Knots to MPH. The real-world weather seems to be accurate and closely mimics the conditions out of the field I fly from. I also have a computer that is not the strongest when it comes to flight simulators (limited by GPU - nVidea GT 1030, 2GB). It runs the Vulkan shaders and I can get a very decent FPS during all stages of flight.
The main complaints I do have about this offering is visual realism. Right now I have the runway markers called up for KGDJ. How can we have a choice of 14 - 34 ? No, I can assure you that the runway, while short, is straight. Simple error, but obvious to even a pre-solo SP like myself. I am running the graphics a high settings, but sadly they just don't compare to the eye-candy offered in MSFS 2020. It just doesn't have the little visual cues I use for even my pattern work. On the 14 approach, I have a spot picked out for downwind leg alignment, and a certain spot to turn base at - plus another one a little further down if it's gusty and I want a longer final to ensure that I am stabilized. Neither of those points are there. The same goes for the other visual cues I look for when "practicing" pattern work at KCPT or KMWL. So, I use MSFS 2020 (on low settings) to be able to find and use those visual cues. If I am practicing maneuvers though, it's X-Plane all the way. I don't have access to a G-1000 cockpit, and MSFS 2020 doesn't offer a sixpack steam gauge C-172 in the package level I purchased. I have tried to download the "free" version of one, but I haven't been successful at getting it loaded into the hangar.
FlightGear 2020.3 is "buggy". But, it's free and uses a lot of the same maps used in X-Plane 11.
If X-Plane 12 can get to the level of realism for the scenery what MSFS 2020 does - while maintaining the excellent physics and modeling of the C-172, I will really consider upgrading!
I consider the flight simulator as a useful tool for a Student PIlot. I don't use it as a "game". I will confess to flying and trying to locate our home and ranch, not identifiable with X-Pane 11, but very, very accurately presented in MSFS 2020.
Saitek/Logitech Yoke, Throttle Quadrant, Rudder Pedals (really dislike the rudder pedals).
Computer: i7 7100, 16GB RAM, 1 TB SSD, Zotac GForce (nVidea) GT 1030 w/2GB DDR5 VRAM. Monitor is a surplus 32" HDTV