What is a good peacock is sort of a funny question! They're all good! Which one is best for your situation depends on the size of your tank, your goals and the other tank inhabitants.
Smallish tanks, like a 55, need smaller, less aggressive peacocks to work. A colony of blue orchids, for example, can even work very well in a 45 gallon.
For a larger tank, say a 75, your options increase. You can do an all male peacock/hap tank in this. "Good" peacocks in this setting is anything that doesn't look like anyone else (if going all male) or whatever you want in terms of breeding colony.
Be forwarned, though, that OBs tend to me among the most aggressive type of peacock, probably because its lineage is a bit suspect. If you have a larger tank and want to keep the OB, then "good" peacocks for the tank would be tougher, more aggressive ones, such as the jacobfriberghi ones.