classic-capitan because all the mods I use are for 14.6 and I'm not going to do a mod and world purge for better graphics
Maybe you misunderstand modding or installing mods. If the ID of the mod remains constant and you have the same set of mods, save games will still be compatible and will still be able to load.
No one is going to keep their mods updated for old versions because it's useless to do so. It's better to keep it up to date with the latest version, because it's likely that the older versions might not support the types of things people are trying to do.