At the end of the day when it comes to programming emulators, the coders are as good as they are, and emulation is always 98%, always something that don't work and the coder can't fix due to lack of understanding. Remember most of these emulators are made by a couple of people, unlike things like MAME which is made by a whole team...
One Emulator may run the games perfectly, but rellie on hacks that break other games... Swings n roundabouts
MAME is a swine for this ^^
Best option grab a bunch of emulators on a said system and try em all. Everyones a Critic....