The real value, in my opinion, is in PSA 9’s. If you knew how many CGC 10’s and BGS 9.5’s existed due to cross grading of PSA 9’s it would make your head spin. Take advantage of the HUGE discount for cards with basically the same condition. The only caveat is having to be diligent about checking the condition of the 9 you buy. The advantage of the 9 is also the disadvantage. Takes more work but potentially lots of upside for your collection.
The golden rule is and will always be: " Buy the card. Not the grade. "
And secondly: “Buy what makes you happy.”