Estimated horsepower
Whren I try to choose an engine or other high performance auto part, I look for a company that specializes in that type of part. If it is valvetrain related I stay with companies that are making camshafts or who only make that particular part as a major part of their business.
Private label parts with names attached to them like JEGS or SUMMIT or BIG END are out there to find the people who put price ahead of quality.
If you only want to pay in the $100 range for rocker arms you will probably get Chinese origin parts.
Good rocker arms are $250-$350 and you can expect USA origin and better quality.
COMP CAMS, HARLAND SHARP, LUNATI, CRANE, CROWER are quality names to look for.