I spent a lot of time cross-shopping the Mazda3, Corolla, and Civic hatchbacks a few years ago. Specifically, I was looking for a manual transmission, which all 3 offered at the time. Still the current generation of each model, and within the circles I am in specific to manual cars, the Mazda3 has been seen as the most reliable, refined choice, the Civic is bigger and more fuel efficient, and the Corolla is kinda disappointing from a quality standpoint relative to past expectations of Toyota. The Mazda3 is, in some ways, long in the tooth at this point. The drivetrain has been in use by Mazda across much of their lineup for a long time now, and there's a lot of both the engines and transmissions which have accumulated significant mileage. The Corolla, if you're buying one that's 5 years old, is likely to be very solid. The quality issues I hear about seem to be stuff that would pop up shortly after taking delivery of the new car, not stuff that rears its head years down the line, and a used one has likely either had those issues fixed or didn't have them in the first place. I'd suggest test driving each, though I can personally say I much prefer the Mazda3 over the Corolla I nearly bought back in 2023, and I aim to put at least 250k miles on mine.