buy what ever feels best in your hands, seems to appeal to your logic in it's working, and is the best camera for your budjet.

Don't overlook the cost of lens, and what you get for your money thier also. Lens is where you are going to spend a lot of your money if you really get into photography. Along with the filters, bags, tripods, flashes etc.

Most camera's come with a kit lens, look at those and price out the camera seperately without the lens. Make sure your getting a great camera with a decent lens.

Example, the Canon t3i is a smaller camera which a lot of women like because of that, but is not as fast or duralble as a 60D or 7D. You also have the 5D which is a full frame camera. Dedending on what kind of pictures you plan on taking and how much money you have will determine which camera you choose.

this is just a usually kit, but not always.
t3i. comes with a 18-55mm lens, the lens is about $200.00 if you buy it seperately.
60D comes with an 18-135mm lens which is about $500.00, again if you buy it seperately.
7D same lens as above, and the
5Dmark3 comes with an L-lens (professional) which is about $1100.00

You can use any of the lens on any of the camera's. I just don't recommend buying a t3i and then getting an $1100.00 pro lens. It can be done, but not the best combo.

Nikon has a different set up, as well as Sony. My understanding is Olympus is in big finacial trouble, so maybe stay away from them, not because they don't make a good camera, just they may not be there in the future.

Also consider,are you a real strong person, can you hold a larger camera steady, do you have small hands, etc. All of these things should factor into you descission.

Good luck and the best advice I can give is go to a camera store several times and play with them all. Do research on the internet, and ask around from other photographers.