All three of these lie flat. That is not the thing to choose on.
The question worth asking is what each one looks like after two years of being opened, closed, carried and occasionally dropped — because a binding that only has to survive a slideshow is a different problem from one that lives on a kitchen counter or a workbench.
What they actually are
Spiral, also called coil. One continuous plastic filament wound through a row of round holes. The one most people picture when they say spiral bound.
Wire-O, also called twin loop. Paired metal loops crimped shut through rectangular slots. The crisper, more formal-looking one.
Comb. A plastic spine with fingers that curl through rectangular slots. The one from school report covers.
How each one fails
This is the part that decides it.
| Spiral | Wire-O | Comb | |
|---|---|---|---|
| Dropped on the corner | Deforms, springs back | Crushes permanently | Fingers splay |
| Pages turned daily | Holds | Holds | Slots tear over time |
| 360° fold-back | Yes | Yes | Not reliably |
| Reopenable to add pages | No | No | Yes |
| Relative cost | Lowest | ~15¢ more per book | Lowest |
Spiral's advantage is entirely in that first row. Plastic filament is springy: step on a coil-bound book and it will come back. Wire-O in the same situation takes a permanent flat spot in the loops, and after that the pages catch on every turn. It is the reason field guides, shop manuals and anything that lives in a bag are almost always coil.
Wire-O's advantage is that it looks better and turns more crisply when it is new, because the paired loops hold the pages in a straighter line. For a report that sits on a desk and gets read a dozen times, it is the nicer object.
Comb's advantage is unique and worth knowing: it is the only one of the three you can open again. If you genuinely need to add or swap pages later — a recipe binder you keep extending, a manual that gets revisions — comb is the answer despite everything else on the list.
The 360° question
Coil and Wire-O both fold all the way back on themselves, so the book takes up one page of counter space rather than two. Comb resists it, and forcing it stresses the slots.
If your reason for rebinding is that you are short of bench or counter space, that narrows it to two immediately.
So
- Kitchen, workshop, music stand, anywhere it gets handled hard — spiral.
- Presentation piece that stays on a desk — Wire-O, if you like the look enough to pay a little more and accept that a drop is fatal.
- A document you will need to add pages to — comb, and nothing else.
For rebinding a book you already own, it is nearly always spiral. The book has already proved it gets used, which is the whole argument.