Canon’s 5d video is surprisingly good and I have found that I’m using it alot for recording sunsets and the HD resolution is just something you need to see. The built mono recording system is ok??, however I will take it for now. Believe me the HD video on this is very good.

In summary, Nikon provides a great system for landscapes and sports and a great selection of lenses. Canon provides an excellent system and one I prefer for landscapes and video. Bottom line is, you really need to know what your personal preferences are before purchase. If available do some trial shots with the camera of your choice (bring a memory card) and your favorite lens and see if the results meet your expectations.

You can only compare brands based on what you are looking for, so for your info I am looking for a small, portable, durable system without sacrificing image quality. Therefore it follows that my requirements are:
1) APS-C system. I am not willing to sacrifice enough to go with 4/3, but I don’w want the weight of FF.
2) Sealed magnesium body. For durability.
3) prime lens selection. To save weight/size and (where possible) cost.

Some comments on brands:

Canon:
– Strong in the high end and the low end, but they have a big gap in the middle. The high end is great with big fast FF cameras and big fast f2.8 zooms. The low end is great with light bodies and consumer zooms. In the middle you have the 50d which competes well with under $1000 segment but lacks the features of a Nikon d300 or pentax k7 top of the line APS-C cameras. To get better than the T1i (other than body material) you have to go to the 5D2, and pay $2000 more.

– Cheap primes more expensive. If you want high image quality at a lower price/weight one option is cheap primes. Canon has only one EF-s prime, their cheap EF primes are more expensive (at least in Canada) than the Nikon equivalent.

Nikon:
– Great mid range body in the d300 (best autofocus and metering between $1k and $2k).
– Good range of cheap primes. Need more DX primes to reduce weight/size, but better.
– In the low end they are eliminating the in body motor, which means the low end bodies can’t use the cheap primes!! Who knows how long they will support the motor in the mid range, so your lenses may lose some functionality with your next body.

Sony:
– Only one camera choice (A700), and it lacks most of the features of the competing brands.
– Anything other than consumer zooms is expensive!!
– Poor selection of prime lenses.

Pentax:
– K7 has most of the features of the D300 (plus video, which is a bonus rather than make or break for me), but in a body that is much smaller and lighter.
– High iso noise is a little worse than the competition
– Pentax has a full line of compact/light lenses made for APS-C. The lenses are a little more expensive, and have higher f-stop (generally 2/3 stop slower), but are half the size/weight. They also benefit from the stabilised body, which counteracts most of the speed difference.
– Lens build quality is better than the competition, and image quality is equal or better.
– being a smaller company the accessories and lens line-up are more focused on the high end consumer market. So they don’t have the selection of specialty lenses that are available for Nikon or canon (tilt shift lenses, 400mm+ Super Tela lenses, etc.)
– Generally their predictive autofocus is behind the competition. The K-7 is said to have improved, but it is not near as sophisticated as the Nikon.

DISCLAIMER:
This is all based on research, and I have only handled the cameras briefly in the store. All these companies could fit my needs (backpacking/travel/family/experimentation). The question is: which one fits best?
Right now it is looking like Pentax because a lighter system is more likely to come out of the closet more often. It might have worse performance in low light, but the best camera is the one you have on you when you want to take a picture.