I don't own either but have shot both. I prefer the Glock because it felt better in my hand. But my edc is a G23 so it felt more like what I'm used to.
One of my co-workers owns the Ruger. We went to the range and shot both his LC9s and my G43. He preferred my Glock over the Ruger, as he said it was more comfortable to shoot. We ended up going to a shop that had the G43 in stock and he bought one. He still has the Ruger, but says it's only a backup to his new carry single stack.
I realize that this is a totally objective statement, but the Glock seems like a higher quality handgun, the Ruger seems cheep to me. It costs less, so there you go. I've owned both and got rid of the Ruger. My G43 is 100% reliable, the Ruger wasn't. I got a lot of stovepipes, sent it back to Ruger twice. They didn't fix it.
Had the LC9S Pro. Shot it well enough but the super thin recessed grip at the front was too thin even for my super short fingers. Never felt I could close my hands tightly enough. The G43 fits fine.
Shot them both, was able to hit better with the LC9S Pro. I own a G19 and G34 so not hating on the G43, but the LC9S was just better for me. If considering a small single stack 9 try to shoot them both (I'd also shoot the Shield if you can). YMMV.