Of course the playing is important but writing and the establishing of what you are going for is prime too.
I would like to play with electronic keyboards again.
Start with the titles, and then build the music that goes with them.
It's hard to avoid the past but one goes forward.
The most obvious thing you can't do with a guitar synthesizer is to really sound like a guitar.
My favorite sounds are the high, spacey ones that are very ambient.