Which PCR is right reflection of position? Volume wise or OI WISE?

General
2

I guess its best to use volumes. PCR is calculated by dividing the number of put options traded by the number of call options being traded.

3

PCR (OI) vs PCR (change in OI) vs PCR(Volume) :

amongst the above three ;
which is the most reliable and which is the 2nd most reliable and which is the 3rd reliable ?