I've done obliques with both a PA28 and a C172 and if it's oblique photos you want, a PA28 with the door off is the only way to go. No wing struts or wheel struts to get in the way, no need for any out of balance flying.
Sitting in the front seat of the PA28 puts you just in line with the leading edge of the wing and flying a nice gentle arc past your subject gives the photographer an excellent field of view.
AMI photography were based out of Christchurch I think, many years ago, all they did was oblique photos of farms and farm homesteads, all they ever used was a PA28.
If it's verticals you want then any aircraft with a hatch in the floor will do.
Edit: remembered name of operator.
Last edited by 27/09; 5th Dec 2011 at 20:24.