20K hands isn't shit
especially for categorizing which tables are best

anyway, in fixed limit you can use a consistent PF strategy because opening too loose vs. fish is a preflop mistake, but you're swapping mistakes for their post-flop mistakes
likewise, tight players might fold their blinds more often even though they'll play post-flop more reasonably

and post-flop you should make adjustments that are based on players, not tables