Being an LTVP holder or an S Pass holder does not mean that one is more eligible than the others. There are various other factors that ICA considers before approving your PR application. However, there is one significant difference.
An LTVP holder can apply through Sponsored scheme only, where the spouse of the LTVP holder will sponsor their PR application. In comparison, an S Pass holder is eligible to apply under the Sponsored scheme as well as the PTS scheme.
Other than this there is frankly not much difference in the standings of either person to get PR. In general family scheme has better chances of approval compared to PTS scheme.