NormT is a GM fanboy; he doesn't talk about or suggest anything else, so he's not a credible source of information about any other car. The GMC Acadia is on Consumer Reports' 10 least reliable cars list. The Acadia All-Terrain can be optioned with 7 seats, not just 5. It is a mediocre SUV. The Acadia does not handle as well as the CX-9 as Car and Driver wrote, "The Acadia very nearly kept pace with the Mazda CX-9 in our cornering test, but it did so with far more drama than the buttoned-down Mazda...the steering feels strictly average." The fact was that the CX-9 barely beats the Acadia in facts, but the actual behind-the-wheel feeling is much better in the Mazda. The only things worth mentioning about the Acadia is that the infotainment system is good and it looks nice from the outside (if fake chrome is your kind of thing).The ride was overly firm and interior fit and finish was poor.
The CX-9 is a beautiful SUV. It's the most nimble and fun to drive 3 row mainstream SUV, more so than the Acadia and Highlander. Has very good driving dynamics and is comfortable. Fits your top 3 priorities perfectly. It is not as practical as the Highlander and is its only major drawback. It dropped significantly in reliability this year because of the infotainment system rebooting randomly, not because of mechanical defects. The CX-9 is on Car and Driver's 2017 10 best cars list. The 3rd row is cramped. Acadia: 25 mpg combined. CX-9: 28 mpg. Highlander: 26 mpg. It is not as good a value as the Highlander. The CX-9 takes premium fuel to get the optimal HP, but it is also fine with regular.
The Toyota Highlander will be the most reliable in the segment. It is more practical than the Acadia and CX-9 especially. Extremely boring to drive. It is more comfortable than the CX-9 and Acadia. IMO, exterior styling is average or better and interior is pretty nice. All active safety features are standard, which is a big deal. The 3rd row is cramped. It is a better value than the CX-9. It does not handle as well as the CX-9 and Acadia.
The Kia Sorento is a very nice-driving SUV. You should test drive one, although it goes against all your priorities. It has the longest powertrain warranty in the business.
If you want practicality and top-notch reliability, go for the Highlander. Your priorities say you want the CX-9. Personally, I would probably go for the CX-9. Good luck!