The "best" cameras depend on preference but usually cannon and nikon are considered the major camera makers in America. And the best resolution cameras they offer are the cannon EOS-1Ds Mark III at 21.1 mega-pixels and the nikon D3X at 24.5 mega-pixels.
If you want the best resolution for your pictures, you should try to buy a DSLR Digital Camera. Unfortunatelly, these can be very expensive, but they worth every cent you spent on it.
The best camera depends on what your budget is whether you're looking for a point and shoot or DSLR. You can't go wrong with something from Canon or Nikon.
