We used to have a 2013 CX-9 Touring which we traded for Tacoma in 2017 because we needed to haul odd-sized items for a few years. Now that our 3 kids are getting bigger (and we no longer haul odd-sized items), we eventually found ourselves back in a 2018 CX-9 GT (last month). After test driving many other 3-row SUVs (in this price range), Mazda still has the best handling and driving SUV.
When comparing the 1st and 2nd gens, I feel the biggest changes are in engine and in the technology...everything else is minor. Handling is still on par with gen 1's handling. This includes vehicle maneuverability as well as transmission smoothness.
First and foremost, I though the 4-cylinder would be a bit of let-down since I knew how the V6 used to drive. I am happy to report that it is much better than the V6 in just about every way and am extremely happy with it. The only way it may fall behind the V6 is if you really load down the vehicle (ie, towing something). Otherwise, it is peppier, torquier, and more efficient than the V6. And that is all down in the lower RPM range where the majority of my daily driving occurs. Reliability is the only one that we won't know until later down the road, but a warranty will usually cover you if it ends-up falling short. By then, it will be time to trade in for the in-line 6 or the Skyactive-X! lol
All of the tech upgrades are a huge step up over our gen 1 (which had a tech package of some sort). The HUD (aka, active driving display) is just plain awesome! I thought it was just a nice-to-have feature when researching, but after only 2 weeks of driving the CX-9 daily, I really feel odd when in another car without it. I just wish it would work with Google Maps driving directions (like it does with the OEM nav).
Also with the tech upgrades, the headlights are a big improvement over the 1st gen...especially if you have the adaptive/auto lighting. The adaptive cruise control is also quite good (better than what Toyota has in its now standard TSS).
The headunit with Nav is not a huge upgrade, but it can be had with Android Auto/Apple CarPlay finally! I had it installed in our 2018 without any issue. It takes a few days to get used to the wheel interface (instead of touchscreen), but it is now future proof vs the already outdated OEM maps and the Gracenote album art database.
Our only real concern (when testing gen 2) was that we noticed is that the rear visibility seems slightly less than gen 1. It initially had my wife concerned after our first test drive, but with all of the tech goodies in the GT, all worries went to the way-side because it definitely helps minimizes the issues with those blind spots.
You won't regret the gen 2 once you test it out (assuming the seats are still to your liking). Take the time to do an extended test drive after really dialing in your seating position.
Honestly, I feel the seats are better in gen 2 over the gen 1. I think this goes to show that this is more subjective than the driving characteristics tend to be. However, keep in mind that we had a couple years in the Tacoma which had far worse seating than the CX-9. lol Anyways, the driver seat now has memory function...that was one thing my wife and I hated in the gen 1 (adjust a power seat and mirrors every other day was a PITA because it was so slow). Now, we just click a button that does it all for me before I even start the engine (except the rear-view mirror). I would also note that I liked the CX-9 seats over the CX-5 seats (which I drove for a full day while they installed my Android Auto upgrade). It wasn't much of a difference, but it was noticeable for me. Oh, yet another note is that my CX-9 was 1 year old when we bought it...so our seats may have already been broken in.
I also believe that the 2nd and 3rd row seats have been improved based on what I remember from our gen CX-9, but take that with a grain of salt since I basically never sat back there.
Hope that helps and I am glad that you are okay after your accident!