Cross-Cut or Micro-Cut for Home and Small Office
For most people this is the only real decision, and it comes down to what you shred and how much of it.
Cross cut
Cuts in two directions, producing small rectangles. Adequate for ordinary household paperwork and usually faster with a fuller bin per sheet shredded.
Micro cut
Much smaller particles, noticeably more secure, and the bin fills faster by volume. Sensible where documents contain identity or financial detail.
Volume matters more than people expect
If you shred a few sheets a week, either will do. If you clear a filing drawer twice a year in one sitting, look at sheet capacity and run time before the cut type.
Cards and discs
If you need to destroy bank cards, check the machine explicitly supports it and whether it has a separate slot. Feeding a card into a paper-only mechanism is how blades get damaged.