What's the best setting to get the best quality?

[LunaMoo]

Just use texture pack someone already made for those games, yeah you said no modding, but really:
- texture replacement,
- renderng resolution.

Are features that give you the most visual quality difference and that's the one you're still not using.

When using SSAA shader you're actually ignoring selected render res to SS multiplier(which can be edited in the shader ini file) of the given shader, which in SSAA x2 is twice of your display so can be x8 render res on 1080p display, but x16 on 4k display and soo on, but having equal double is nicer than some random value and the fact is the more pixel density of your monitor, the less AA you need.

There's also MSAA in new PPSSPP versions, can in some ways be better for of AA than post process effects, but it's not that much of a difference from SSAA

Post process effects are heavily subjective and not an universal enhancement.

Texture scaling is like an automatic poor version of texture replacement, fits some games, looks terrible in others, it's again very subjective.

We also have some new texture filtering method "auto max quality", but it's still buggy and not that much of a difference as the above anyway.

Honorable mention for "lower resolution for effects" hack, this is a must in many games that use effects which break when increasing render res, however not all games use it and it doesn't work in all games that have such effects either so it's not a big feature in the end.