If you prefer A5s with 30mm rings rather than 25mm rings, as I do, then heaven is often a personal size with 30mm rings. They are pretty hard to come by in newer binders, but there are several older models with larger rings.
I have two Cavendishes and a Portland grand, all with rings in the vicinity of 31mm. It makes such a difference. Stuffing binders is tough on the rings and makes turning pages difficult. With 31mm rings you can fit so much more in. And on the vintage binders, those rings snap tight as a drum.
One of my Cavendishes is navy blue – how wonderful to have a deep blue binder. Like greens, blues are hard to come by. They should be more widely available as alternative neutrals.
These all came from bouteia on eBay. Their shop is so worth looking at if you are into vintage binders as they have pretty much everything and it is all brand new and beautifully packaged in that very rare item these days – A Filofax Box!
In the photographs below (which are a bit blurry in places – profuse apologies but I could not get them any clearer), the two with back zippers are Cavendishes and the other one is a Portland Grand. They all have two pen loops. The Portland has a square-ish spine.