Hello,
Some filter are good for one system and some for other. Especially it relates to Blargg’s NTSC filter. Some emu has it hardcoded but some doesn’t. Using this as a general filter for all systems isn’t a good idea as it depends heavy on resolution. So it’s good for SNES but it ruins Genesis games. And turn if off/on every time I want to play on a system that has an issue with it is really annoying.
Maybe it would be even better to hardcode Blargg’s NTSC filter to Snes9x but I think it’s hard way. And besides it could be issues with other filter too.
And last but not least. Crop overscan option should be Core based too.