I prefer the “Open time signature (plain)” glyph to the standard one, as I feel the serif X looks better in the same score with fancy/ornate “normal” time signatures. But the only option to use it (I think) is to choose “Plain font” for all time signatures in Layout Options. So if I want the serif X but normal time signatures for everything else, I think the only way to do it is to replace the regular “Open time signature” glyph with the serif X from the plain version.
It would be nice to have an option, maybe in the properties panel or in Engraving Options (or maybe even Layout Options), to switch to the serif glyph as the default for open signatures in that score (or layout). Not a major thing but it would be nice to be able to avoid the workaround. Thanks!