I'm using Filezilla for a long time now and i never had problems with it, works like a charm, just the only problem i have is with deleting alot of files haha, but i guess this is not fixable.
I have only used FileZilla, though i never used WinsCP because i have never heard about, when i was new in these type of things, i only got suggested to use FileZilla.
I have used FileZilla, I dont like how FileZilla works( It takes forever to upload something which has alot of files ) but still never thought of trying WinSCP, I did try WinSCP once but that was on a friend's machine not for myself.