I buy mainly NON-Jamma PCB  (old Original classics, like Donkey Kong, Popeye, QBert, Pacman..etc..)  , i have few jamma but game which interrest me are mainly non JAMMA.
I buy Lot MVS  Neo Geo too.  I like this format... it is very easy to store!
In fact, on  my mame cab , i have only roms i have the PCB or the MVS.  I use my Front End and MAME , only because you don't have to unplug and plug the PCB when you want change game , and for some PCB i don't have the JAMMA convertor... so.. mame.
Sometimes i use mame with a ROm i don't have the PCB , in fact, just to test, if it worth to buy it or not.  
I own about 40 PCBs (30 NON Jamma)  and 80 MVS in my collection.