I have shot both. I'm torn. Both have their strong points and weak points.
Currently, I own the Shield. My brother purchased the LC9s. I actually shot the Ruger better. Probably has something to do with the excellent trigger on it. However, I'm getting the Apex trigger spring set, and the "glock type" Apex trigger. I suspect that the trigger feel issue will be less of a deciding factor at that point.
The Shield does shoot softer, but the Ruger didn't kick nearly as much as I was expecting [due to the lighter weight]. Both guns are capable of superb accuracy for their sizes, but I shot a slightly tighter group with the Ruger.
The grip angle on the Shield is a bit too angled [I have to push the front of the gun down a bit to light up the dots]. The Ruger seems to be a bit not angled enough [I have to raise the front of the gun up a tad to light up the sights]. That's a personal issue, though.
The Shield comes with two magazines. For the Ruger, you'll have to purchase a second magazine off the shelf. Both are close to the same price for purchasing.
I agree that you should see if you have a range where you can shoot them first. If not, then go with which one you feel has the best ergos and then just go for it.