Despite enjoying multiple models of the phone I currently have I won't get a new model because the sensor is on the power button. Back of the phone supremacy under screen is OK if it works, power button sensor can burn in a hole.
Back of the phone was the best. I could pull my phone out of my pocket and unlock my phone in single motion and decent grip. Plus the swipe gestures for accessing the notifications bar...
I have a Pixel 6 with underscreen fingerprint reader and I love it. Only wish it was a tad faster and a little less prone to not recognising my thumb occasionally. Hopefully the tech is already better in newer models.