It's early, but we already have both "apple" and "apple2" tags. My thought is we should use "apple2" for anything related to Apple II, as the old 128K Macs are very much retro.
I'm not convinced we need to subdivide into separate tags for Apple ][+ vs. Apple //e, but the Apple IIgs was a very different system. Since that's generally written with "II" rather than "][" or "//", I think "appleiigs" makes sense as a tag.