We've had Wonka since new in August, 2019, and a used WOZ since August, 2021. My vote is Wonka.
Some notes: with the latest Wonka code (2.03) the games can generally be long if you are a decent player and the game is tuned well (level, newish rings, clean playfield). However, with the latest code (default setting), you finally have the feeling that you can make some progress. The theme integration & videos are great - better than WOZ, IMO. However, I like Wonka movie better than WOZ. Newest code even added some more video synced with sound relative to 1.x code. There are more (ie varied) chances for different multiballs in Wonka.
WOZ is a drain monster - especially that left out lane. So, games do tend to be shorter, even for a better player. I do kind of like the post between the flippers. I like the right out lane Toto rollovers with the 1- or 2-shot chance for a ball save. The ball save chance given by the State Fair balloon pop on the left is so difficult it is ridiculous IMO. I've only saved a ball once so far. I groan when I get it, and am tempted to let the auto-plunge just drain. The integration of WOZ is great, and it is a beautiful machine. The upper playfields are actually interesting with something to achieve.
But, I still choose Wonka.
Wonka WOZ together (resized).jpg