The length and breadth of my experience with the PX4 consists of holding one at a gun show. I no longer remember which PX4 it was, what caliber, etc. That being the case, I'm going to pass on voting. That said, the PX4 comes from a reputable manufacturer, has the same capacity as the G19, and gets pretty good marks from the owners. That's from what I've read on the internet, so it must be true, right?.
I do have a Gen 4 G19, which is my EDC. I will not claim that Glocks are "Perfection," as mine broke at about 400 rounds. The slide lock spring broke, but it was a cheap and easy fix. If I can fix it (I did), you can, too. In the ~1100 rounds since then, she's been nearly flawless. Not entirely, but nearly. She eats any ammo I feed her and no doubt shoots as well as my eyes and limited skillset will allow. Takedown for maintenance is simple. Aftermarket support is huge. If a company makes a widget for a pistol, it makes that widget for Glocks.
There are a lot of people who do not like the way Glocks feel in their hands. I'm not one of them, but I think it's a valid point, especially when there are so many other perfectly suitable pistols out there as competition. It would be different if the G19 were the only reliable ~4" barrel, ~15 round, 9mm polymer pistol out there. It's not. I like the way the G4 G19 feels, but if I remember correctly, I liked the way the PX4 that I held felt, too. That's a decision that you'll have to make.
If you can shoot 'em side-by-side, do so. IMHO, that will tell you more than we can. Good luck!