The best camera is the one you have with you. You know, the one you actually know how to use to get pictures you like.
You can make professional photographs with an old Yashica MAT-124 on film, though I personally prefer a Leica M7 (film) or M8 (digital) with any Summicron or Summilux lens.
Rangefinder cameras like Leicas and digital point-and-shoots have the advantage of small size and weight. They're good for 90% of your photography. Leicas are stratospherically-priced, so they're probably not a practical option.
You need special-purpose equipment for certain subjects. The best platform for shooting nearly anything is
any dSLR camera mating to a
large lens selection. That usually means Nikon or Canon, though Sony (Konica/Minolta), Olympus and Pentax give you high-quality lens options.
My own gear includes lenses from 16mm to 500mm, and Canon EOS cameras - 5D mark II, 1D mark II, and 20D. I use a Leica M8 and 25mm, 35mm, 50mm and 90mm lenses when I'm traveling light.
More important is recognition of good light, then putting something interesting in it.
If you're shooting products like food, or architecture, or events/people, learn to use strobes, preferably off-camera, to create the light you want. Look up David Hobby at
www.strobist.com, or try books by Joe McNally or Kirk Tuck to learn how to light.