Minolta Dynax 650si / Maxxum 650si
The 650si is basically the 600si with a couple of additional features. It adds a 'panorama' feature which does little but place a mask of the film plane to make the resulting image narrower than standard 35mm frame. This feature was add to some cameras during the 90's in an attempt to narrow the feature differences between 35mm and APS formats. The 650si also adds a data back as standard. You might not need or use either of these features but if you can't find a 600si for decent money look for the less well-known 650si.