I’ve spent a lot of time with both, and hands down the wired one is far more flakey. Granted I think that’s more a Mazda software issue, but a solid 10% of the time I get “CarPlay failed” and the only way to fix it is to turn the car on and off. Never once had an issue with wireless in a Hyundai.
In my Mazda the wired CarPlay also seems to fail a lot. But whenever I rent a car with wireless CarPlay it's been fine. Take this one anecdote for what it's worth.
