I'm not gonna pretend this is a fair or unbiased contest. I learnt Avid first and I think it's brilliant, but for what its worth he're s a few why Avid is better than FCP and a few reasons why FCP is better than Avid. Here I am comparing only the systems I use, Avid Media Composer 4 (usually with an Adrenaline) and Final Cut Studio 3
When Avid says real time it means it. Yes you have to use computer that's up to it, yes you have to use Avid codecs to edit in, but if you do that then you know without a shadow of a doubt that everything that has a little green dot will play back, without delay at a full frame rate and with full resolution. No rendering (except for the occasional complex effect), none of this Unlimited RT business (what kind of use is realtime playback if its not the full res and framerate??), it just works. And now that Avid accepts multiple resolutions and framerates within a sequence (and still manages realtime playback) there really are no arguments here.
After using Final Cut for a while I rejoiced the first time I got back on an Avid and used trim mode. It just makes sense. Its fast, efficient and lets me analyse every cut with ease and make sure the pace is frame perfect, (which is and editors job yes?). FCP7 has brought in some features that are pretty similar to trim mode and I appreciate the effort on their part, but I still prefer the way Avid works. In terms of my editing workflow, going into trim mode after I have done my first assemble just makes sense to me.
If you plan your media management well then FCP can be great. Certainly relinking to media when it goes offline is a hell of a lot easier. But I find that FCP allows you to be sloppy all too easily, and evidently people will be sloppy when they are allowed to be. Doing online work for independent films can feel like a military operation to get all the media you need. Avid is strict but that forces you to be neat. All your media is kept together and when you consolidate it works reliably.
Without a doubt the main reason I use FCP. So much better and so much more intuitive than trying to use Media Composer to grade, this tool sets my work apart from others. No, its not as quick or accurate as a DaVinci or Pogle or anything, but chuck a Blackmagic or AJA card and a broadcast monitor on your MacPro and you have a viable broadcast finishing solution for a ridiculous fraction of the cost of the those other systems.
Red Codec Support
Can't argue with FCPs RED support. Alot of the projects I work on are shot on RED so its good to have a viable workflow that will allow you to at finish your project at a 2 or 4k resolution from the original R3D files (although this will eat your MacPro for breakfast). In defence of Media Composer, it has never claimed to be a finishing solution, it is a cutting machine. And it does offline RED footage well.
It was a close call in the codec wars until Apple released this. I only use this to transcode RED stuff too if I'm not going to have the time to go back to the R3D. If it's just HDV or XDCAM or something then 422HQ is good enough. Grading from it in colour is amazingly quick and painless and you can certainly push things further than you would dare with 422 or DNxHD.