decide what you want a camera for
decide what features you think are important
decide a budget
If you are buying a dSLR then I doubt you will find any significant difference between each of the major camera makers offerings whether thats Canon, Nikon, Olympus, Pentax, Sony Samsung or Sigma
theres a lot of bias, prejudice and frankly bollux talked about camera, especially here. Many claim only professionals use Nikon or mebbe Canon. Nikon lenses are better than blah, the fact is that there is precious little to differentiate the cameras at the respective price points. yes spending god knows how many thousand ont he top of the range Nikon or Canon and comparing to the budget Sony, Nikon or whatever you will probably see a difference. but to a beginner you won't. make you own mind up about what features are important or required.
bear in mind many reviews refer to this cameraas menu system being much easier to use (what the review usually means is I have a camera from the same maker and the menu system is familiar to me)
right no there seems to be a good deal on Sony Alpha cmaeras, but Sony isn't a camera maker I hear the Nikon/ Canon fanclub scream.... but Minolta was, and Sony bougth out Minolta's camera division. but Nikon Lenses are better they say, but Sony bought out Carl Zeiss for lens development.
features that may be worth looking at in (no order)
sensor fairly irrelevant once you get above the 5..6Mp
battery capacity , type, number of 'shots' per charge
memory card and type, what size card can it use
ISO range of the camera (theoretically the higher the ISO range the more photos you can take in poor light
quality of the optics you actually buy with your camera. I doubt any lens maker is producing 'poor' kenses, but there are subtle differences and variations some lenses are a bit better than other makers..
size and weight of the camera and selected lenses
speed of focus
number of focus points, number of metering points
BUT above all ease of use, and that comes from practise and dare I say it reading the manual. you may have the most wonderfull camera, if it takes you a while to get the camera awake and selectign the right lens and all the other stuff, it doens't matter how good it is if you've missed the picture
the best camera is undoubtedly the camera you had to hand that took 'that' picture, and if thats a 2Mp camera on the back of a phone so be it.
once you've narrowed down you list of required features look at the serious camera review sites such as dpreveiw.com and others.
make your own mind up, after all its your camera, not someone else's
its your decision, not someone else's