I'd guess one is Ann/Anne and the other maybe MaeMay? Also-rans might be Jean or Jane and maybe Marie or Louise?
I like them both. I think Patricia is a little bit brighter and more cheerful, and if you want nns, there's a good few. Sylvia is pretty, but the only nn I see is Sylvie, which feels weak to me.
So I think I'd choose Patricia, and if I wanted a nn, it would be Tricia.
Before you criticize a man, walk a mile in his shoes. That way, when you criticize him, you're a mile away and you have his shoes!
Steve Martin