In Europe, the grading is Low, Medium and High. In Japan, they use S, SS and SSS. However, none of them are based on pattern. Instead, they are based on the colour intensity and coverage, body shape (the Japanese are critical on the berried shrimp shape too) and posture. In some countries, they will look at the size too. In summary, the grading is kind of based on criteria used in competition.
When comes to pattern, it is more for personal preference. Be it banded, saber-tooth, hinomaru or mosura, they all cost the same price. In Japan, more people prefer banded and saber-tooth than the rest. This is because these pattern will exhibit the best red colour in contrast of white.
Those so called "PRL" from whichever lineage that most seller claims are either they self-breed or they just buy from those cross-breed offspring from those mass-market shrimp farm. Never buy PRL that people claims about the line or cull from which ever tank. Lineage means these shrimp originate from a good shrimp, but they have been crossed breed and produce low quality shrimp after generations. Hence, the shrimp you are buying is just normal shrimp that may looks a little like PRL. If certain PRL tank is able to cull out very low quality shrimp, then those are not good PRL. Hence, don't believe when people claims that these shrimps are cull from PRL tank.