Everyone has its preference mixed of subjective and objective reasons! Sad to get aggressive then. If I can add something usefull to this, these articles from Sanjay helped me choose a LED fixture:
PAR from AI (not all 70 optics unfortunately):
http://www.advancedaquarist.com/2010...ure2#section-1
PAR from Radion:
http://www.advancedaquarist.com/2012/1/aafeature
Spectral tests:
http://www.advancedaquarist.com/2012...aign=clickthru