its really depend on what u want to achieve...hard to decide for you...some people will tell u 12-24...some will say fisheye...some will say both...how you going to decide like this???
On a DSLR, it would be a good range of 18 - 36mm... pretty good for general wide-angle shots. For the 10.5, you have to defish the shots to get a picture without distortion...