The first consideration in the liturgical use of a synthesizer is instrumentation.
Gear is gear.
Just because your synth has a very cool sound doesn't mean you have to find a hymn use it with. For the responsorial psalm, I choose a very warm-sounding electric piano like that of the good old Fender Rhodes. Adding a very mildly wet chorus effect to it helps warm the soul and does not overpower the cantor and assembly. For all songs, the acoustic piano patch is an excellent choice, but be careful with these patches as dominant accompaniment instruments. But even though manufacturers of today's synthesizers have captured the acoustic piano so wonderfully, there are very few Catholic church sound systems that can do it justice.