AVCHD as THE format for HD in camcorders & cameras seems to dominate though. If that view is correct, more and more equipment will go that way going forward... and thus software compatibility will move more quickly in that direction too.
So I'll counter by suggesting the OP goes with the flow. iMovie is not great for working with HD (other than keeping editing very simple). I've never been able to export great quality HD from iMovie as opposed to using a tool like FCP X with the same footage.
We generally buy camcorders to capture slices of life... someone's birthday, christmas, the family trip, etc. 10 or 20 years later and some of that would be listed among our most precious possessions. So, I suggest stepping up from iMovie to FCP X or similar and rendering those precious home movies at the highest possible quality. Many people think of FCP X as iMovie Plus. It's not that hard to learn to use it for this level of need. And it can definitely export some very high quality HD files that look great on stuff like
TV.
One more add-on suggestion: if some of what you shoot is fast moving stuff- like kids playing sports- consider 1080p 60fps camcorders. 60fps is overkill
apple:TV can't even play 60fps natively) but those quicktime renders (h.264) are "buttery smooth" and make for an excellent master file while waiting on
TV or something else to gain that capability. You can always render a 60fps version and 30fps (using the latter with
TV as it is now). Later on- when a future
TV will hopefully support native playback at fps other than 30, you can just swap out the 30fps versions with the 60fps versions.
I've done this for a couple of years now myself with our home movies: Panasonic camcorder 1080p 60ps through Clipwrap to convert the raw video to prores422 files. Import those into FCP X for editing. Export them as prores422 files. Import those into Handbrake and render a 30fps and a 60fps version with the high profile setting. Store the 60fps version as a master file. Import the 30fps version into iTunes and play it on
TV3. Quality is wow impressive... much better than I could ever get out of iMovie. If I need to make a SD DVD for someone else (maybe some other family member not yet on the HD train), working from those master files yields the highest quality DVD video too.
Incidentally, how I got here was a desire to preserve Dolby Digital audio shot on some camcorders since about 2006 or so. iMovie can't do that (it outputs stereo) so I went with FCP X for the audio and then found my way to the above workflow. Home Movie DD surround tends to not be that important for most shoots but it is interesting in some home movies- such as sports- where we can clearly hear fans cheering from behind, left & right or big auditorium events where echos and sound is coming from all around where the camera was located. Some vacation sound can be interesting too (such as having ocean waves behind the camera while filming the family on the beach or being in the tropics and having the sounds of nature hitting from all sides). If OP is getting a pretty good new camcorder, odds are high that it will probably have some form of DD record on it (consider taking advantage of that when you make your final renders).
Since then, I've worked backwards through our home movie archives to maximize quality of the earliest HD shoots done on those early Sony (HDV) camcorders that saved a 1440x1080 HD signal to tape (again, output quality is much better than I could get through iMovie). I now think all of our home movies are available at about the highest quality they can be viewed... all quickly accessible via
TV3.