Since the AME was introduced I have been far more productive because I now almost never wait for a render. The AME is not that much slower, in actual fact it saves you time because you don't have to stop working in AE while renders are running. Sometimes custom players used for things like animated signage are stuck with h.264 in a MOV container so all you have to do is change the extension to get those players to work. Any media player will accept the files without problems. If the video is going directly to the audience then an h,264 MP4 is the most universal format you can find. ProRez is good for a Mac, Cineware (free from GoPro) is also a suitable production format. The proper format depends on the systems your client has in place.

I'd pick a suitable production format for that. Also, H.264 is a very lossy intraframe codec that should never be used for further production or archiving. You should also gently educate your client to the face that QuickTime no longer is working on or guaranteeing support for h.264 QuickTime. MOV's that are really mp4's playback just fine. The big problem is rendering to the MOV container. If the client really needs the movie as h.264 in MOV format then just use the AME to render an MP4 and change the extension.

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