More realistically, try these settings (pictured below) which are for Compressor. Set up FCP to export with these settings through Compressor to enjoy high quality AND fast uploads. You don't want your bitrate too low. Youtube has a bitrate of around 8mbps for 1080p stuff, but that doesn't mean you should upload anywhere near that low of a bitrate. Youtube will always recompress, but it's a good idea to give it the best original file to work with. That said, these settings will result in nearly the same or the same final video quality as a ProRes4444 upload . At least for now. In the future it may make more of a difference if their encoder gets any better.
Also keep in mind that it depends on the browser you use when watching videos on Youtube. They look best in Chrome, have the best (and most stable) framerate on game consoles like the PS4, look worst in Firefox (crushes many colors, especially greens, sometimes even makes the greens look "nuclear", and drops a ton of frames during 60fps playback) and Safari doesn't even support modern codecs like WebM VP8 and MSE & WebM VP9. Visit www.youtube.com/html5 to see what your browser supports.