We always dined by 630 or 7 at the latest and made reservations the night before asking for the same table cuz we enjoyed the waiter. It was never a problem. I think that the reservation is the secret and we enjoyed meeting people so the table we asked for seated 10. It was great!
If you mean "Anytime Dining," I think you made a mistake. There are some folks who prefer that arrangement. but I don't.
(By way of clarification, Princess uses the term "Personal Choice Dining" to mean that a ship offers both "Traditional Dining," with assigned tables at two seatings, and "Anytime Dining," which operates like a restaurant ashore.)
With your experience, what time is the best time to dine?
It depends upon (1) your prefernces and (2) what else you want to do during the evening. The practical reality is that many people with "Anytime Dining" end up eating near the times of the two seatings of "Traditional Dining" because those seatings are timed to mesh with the shows and other featured entertainment.