1. Good or bad preschool is determined by what PARENTS EXPECT.
Some parents only expect preschool to teach ABC and if their kid comes home knowing ABC, it's a good preschool.
Some parents expect preschool to prepare them well enough for Pri sch that there will not be a need for excessive tuition in P1/2.
This is solely by YOUR OWN YARDSTICK. What may be good to me may seem stressful to some parents who do not want their kids to be stressed. What may seem good to other parents may not seem good to me cos they are not teaching enough.
2. PAP = PCF. Are you comparing the KINDY vs the CCC?
CCC = full day program which include meal times, play, nap, etc. I personally find it alright for social interaction but not for academic learning.
PAP kindies, it really depends. The quality and price varies very largely. There are those charging $50-80 a month, others charging $100-180 a month and those charging $200-300 a month. Their curriculum are all different. And it also depends on luck - whether your child gets a good teacher or not.
3. Full day program vs Half day program
There are kindies offering full day program though they are not CCC.
Full day program are more for kids who need a long time to settle down at school.
Depending on the centre/timetable, they kids may not get enough rest.
This really depends on individual kids.
BTW, seems like you have limited your 'search' to PAP/PCF only. There are many affordable and good private operators too. And, you also need to consider your location.
For me, I chose a kindy with strong academic focus.
I want him to have the concept that school = serious learning, not play.
He can play at home. In fact, I dont't even restrict his playtime/TV time. He is free to do anything once he's home (except 1/2 hour of studying/reading with me daily).
In fact, his class is only 2.5 hours but he comes back rather tired cos it's really solid learning and activities, no sitting around doing nothing (or wait for each other in cases of schools with large enrolment).
You can read more about how I chose a preschool here: The Little Ones in My Life