when considering photo equipment keep in mind that the best photographer can create/capture a wonderful picture with the most rudimentary equipment while the most expensive equipment will do little but take a picture in the hands of someone who doesn't understand composition, lighting, etc.
Both Nikon and Canon are recognized leaders in their respective fields, offering various bodies and many lenses. The lens is more important than the body. It is better to splurge for a better quality lens and a less expensive body as any camera made today by Nikon, Canon, etc will capture the same information. Unless you are posting billboard size images, you don't need anything over 12 megapixels.
The Lumix (Panasonic) cameras that AMG references take a different approach and offer a different [and higher quality] experience. One of the interesting aspects that Luix is offering is stitching (not panoramic stitching to create a wider 'scene' image but to make available more pixel information by stitching together more compacted images into one larger image, each smaller image containing more pixel info for higher detail, etc.
I have used Canon and Nikon for 30 years. The D70 was my first DSLR when they first came out an frankly have never found a reason to upgrade. I have instead chosen to invest in lenses. I shoot a lot of indoor hockey (kids) and for anything indoor you need a min aperture of 2.8 (fixed). When you start to look at tele, wide angle or zoom lenses with fixed aperture, you are generally getting into better quality lenses. The difference is quite noticeable.
For shooting outdoors or where a slower speed suffices, you want to look at the VR range of lenses, with built in stabilizers to minimize shake. Both Nikon and Canon offer VR zoom lenses that are great all around lenses. you can put 2 in your bag and you are good to go for 95% of your needs.
Make sure you discuss with the seller - both Nikon and Canon sell 'kit' lenses with their bodies and these are crap.
I do not know why anybody would quote $300 for a D70 - they have not been worth anything on the resale market for more than 2 years and any reputable dealer will tell you the best thing you can do with them is keep them as a second camera. There is nothing wrong with them - they just don't have resale value.
One other consideration is that if you look at the sidelines of any sporting event, 90%+ of the equipment is Canon. That should tell you something.