I dunno if *any* LSP will do much to prevent stuff like that.
Heavily layered KSG is the only LSP I've *ever* had exhibit the "marring that didn't go through to the actual paint" effect, and that was such light marring that normal people in normal lighting couldn't see it at all.
Very slick LSPs tend to shed dirt easily, so it's easier to wash without marring.
"Water spots" is kinda vague..nasty water (acid rain or, conversely, from sprinklers/etc.) will etch right through most any LSP. Most mineral deposit spots will wash/clay/paint-cleaner/polish off without too much trouble. Any LSP that beads will leave spotting when a dirty vehicle gets wet, but that stuff just washes off.
