Understanding your Camera Needs... What is the best Camera to Use?

Different cameras do have their strengths and weaknesses, and these will restrict your possibilities. But the most important restriction - and strength - is always your imagination.
Digital cameras are great for photographing people, not least because you will need to edit your results severely. Better to waste a few electrons than film.

SLR / DSLR Cameras

This is the camera type most widely used by professional photographers because of its flexibility.

Advantages

Accurate viewing and framing. You see from exactly the same viewpoint as the picture is taken - no 'parallax error' Most SLR / DSLR cameras show slightly less than appears on film
Interchangeable lenses give more flexibility and different perspectives
Generally have wide range of shutter speeds and apertures
Modern cameras are highly automated, giving good exposures without much thought.
Auto focus cameras are especially useful with longer focal length lenses.
Dedicated flash units can give accurate flash exposures automatically.

Disadvantages

Generally quite large, so you have more to carry around
Camera size makes them and you quite conspicuous
Shutter and mirror noise can be obtrusive
Time between pressing shutter release and taking picture can be around 30-50ms (longer if camera auto-focuses during this time.).
Viewfinder blacks out briefly while picture is taken

Rangefinder cameras

Used by professionals before the SLR became common in the 1970s, and still preferred by some for covering rapid action. The Leica M series are expensive, but more affordable Konica and Voigtlander models have led to renewed interest.

Advantages

Smaller, quieter and generally less conspicuous than SLR cameras.
Clear viewfinder image with bright line frame enabling areas around subject to be seen, which remains visible during exposure.
Very short lag (usually less than 30ms) between pressing release and exposure.

Disadvantages

Viewfinder is above and to the left of taking lens - has a slightly different view to what appears on film. (parallax error)
Not suitable for long telephoto lens (90mm is about the practical limit)
Generally limited automation - some have auto exposure.
Framing less accurate (still good on most models.)

Compact cameras

Commonly used by amateur photographers, although many professionals carry one in a pocket for when they don't have their full outfit with them.

Advantages

Unobtrusive and in common use; usually quiet.
Zoom lenses generally cover the most useful range for photographing people.
Relatively cheap.
Usually highly automated - exposure, focus, film wind etc

Disadvantages

Extended lag between pressing release and taking picture (often > 500ms)
Built in flash mainly useful in bright light for fill in, gives poor results in low light.

Other types

Many photographers in the middle of the twentieth century preferred the twin lens reflex camera, usually taking 120 film, and used from waist level. Rather than making eye contact with the subject through the pointing lens and viewfinder of the camera, they bowed down in front of it, peering into a box held firmly against their gut.

These cameras, particularly the Rolleiflex and Rolleicord, were quiet and unobtrusive to use, and their large negative allowed for considerable cropping. A few photographers still like to work this way.