What camera should I buy?

One of the most asked questions Ive seen on most forums.

Initially this thread won't address much or may have mistakes, if you still have questions about which camera you want, ask in this thread and I'll update this post with more information.

As far as digital SLRs go, any recent model is capable of producing high quality images, more critical in image quality is choosing the right lens.

So apart from getting the best you can afford (or the cheapest SLR kit you can find) here are some tips:

Image Stabilisation: In-body or in-lens?
If you like to shoot film - in-lens (Canon or Nikon cameras), if you like to adapt old manual film lenses to your digital SLR - in-body (Pentax or Olympus cameras).

Want to shoot both film and digital?
Canon or Nikon with full frame lenses (IS and VR will work on the film cameras too)

Canon full frame lenses - Any Canon EF, Sigma DG, or Tamron Di (No Canon EF-S, Sigma DC, or Tamron Di-II).
Nikon full frame lenses - Any non-DX lens (apparently), DX lenses will mount and work on Nikon film cameras too (apparently), but their image circle wont cover the full frame, thus vignetting, any Sigma DG, or Tamron Di (No Nikon DX, Sigma DC or Tamron Di-II).

Want full frame/35mm digital?
Canon. Canon. Canon.

Specifically, Canon 5D, ~3 years old now, sitll no replacement, still an amazing amount of detail, lowest noise and highest detail of high ISO (yes, better than the D3 and D700), can be had for under $2k for the body, vs $3500 for the Nikon D700.

Want to adapt manual film lenses to digital?
Canon or Olympus.

Absolutely not Nikon (lack of aperture priority metering on many Nikon cameras, cant adapt M42 and others)

Canon - Can adapt M42, T-mount, Nikon F mount, Pentax K, Olympus OM and more, can be used for either Canon film SLR or Canon 5D full frame digital as well as the smaller digital SLRs (40D, 400D, 450D, etc), 1.6x crop factor or 1x crop factor (or no crop factor in other words) for 5D and EOS film SLRs

Olympus - Can the same range of lenses, you will benefit from image stabilisation with the old lenses! 2x crop factor (good for telephoto).

New Olympus mirrorless/prismless camera with Electric Viewfinder - lens mount is roughly 20mm to the film/sensor plane - can adapt Pen F lenses easily, can adapt 16mm lenses! Can adapt Canon FD lenses EASILY! (the Canon FD 800mm f/5.6 is under $2k to buy/import from the U.S. from a reliable site! plus you'd get "IS" on that lens).

I want a digital camera to shoot landscapes
Canon 5D with wide angle (at least 28mm, wider would help, and a 50mm lens)

Portraits and Studio work?
Canon 5D

Sports?
Canon 40D and a 70-200mm f/2.8 lens - under $1900 for 40D + Sigma 70-200mm f/2.8, $2400 for 40D + Canon 70-200mm f/2.8
Nikon D300 and a 70-200mm f/2.8 lens - $2500 for D300 + Sigma 70-200mm f/2.8, $3900 for D300 + Nikon 70-200mm f/2.8

The Nikon and Canon lenses have image stabilisation, Sigma does not, the Nikon lens is rather prohibitively expensive.

If you had the money Id go for the Nikon D300/Sigma combo, it's a bit better camera for sports, larger buffer, can shoot up to 8 photos per second with a battery grip, 40D smaller buffer and 6.5 photos per second.