We did Plaza Inn and the PCH breakfasts in march, and both were fantastic. Plaza Inn has the most characters hands down, but the level of interaction can vary greatly depending on how busy it is. Some folks like to book as early as possible, which does usually mean fewer people competing for attention, but can eat into your morning park hours, while others prefer to hit the park hard first and then do a later breakfast, nearly brunch during one of the last timeslots. Either one works well, and I highly recommend including it.
The PCH surf's up was our first time this year, and it is not on the list of must do every trip. Like a few other commenters, we booked it the day we were leaving as a last taste of magic and it did not disappoint! My oldest surprised me that trip by declaring that Stitch was her favorite character (I did not even know that when I booked the brunch, which was a surprise to the kids), so it made it even MORE magical. The character interactions were great, the food was a bit better than Plaza Inn (although I love both), and it was the perfect way to end the trip. If we could only do one next trip, I would probably do the PCH - but only because we've done Plaza Inn several times.
My sister is planning a trip for spring break 2020 and looking at the princess breakfast, which wasn't available when we were there. Looks pricey but the interactions sound great. Anyone have comments on it recently?