I know this won't be popular here but I think there was a wrong answer. I thought this season it had to be between Wilson or Thomas.
The MVP award has generally went to the best player on the best team in previous seasons or a player that was off the charts better than everyone else.
A'ja was the center piece to both the best offensive and defensive team in the league, all while shooting with an unmatched high efficiency and dealing with the adversity of losing her frontcourt mate Parker pretty early in the season. She was able to impact the game and put her team in winning positions in less times than her peers and only had marginally less points than Stewie and marginally less rebounds than AT despite the minutes played.
AT in a similar vain as A'ja had to step up in the absence of losing her frontcourt partner in Bri Jones early in the season and took the brunt of her absence too. Considering how much the Sun needed her in all aspects of the game and how much she impacted the game I totally get why she would be considered despite not meeting the typical requirements for the MVP in the past 10 years.
As for Stewie she had a good season, but I don't think it compares to the other two. She adapted well to NY and she had some big scoring games but I definitely feel like she wasn't as efficient as A'ja and not as essential as AT was despite not having the same major adversities the other two had to endure in the regular season.