Warpinator is meant only to send/receive files and folders, and requires a supported device on both sides.
QuickDAV lets you send/receive/manage files (meaning you can copy and move files on the host from the client). It doesn’t require a supported device in both sides, since it works with either a WebDAV client or a browser. So as long as one device can run QuickDAV, and the other has at least a browser, it’ll work. (QuickDAV works with a Sega Dreamcast!)
Warpinator is incredibly easy to use. Open the app on both machines, select the other machine, select the file/folder, send.
QuickDAV is a bit harder. Open the app on one of the machines, then type the information from the app into the client/browser on the other machine. Then you can download/upload/manage.