Format is usually chosen from a catalogue. It should be chosen from a description of the desk it is going on.

Easel: minimum footprint

Borrows vertical space, presents its face nearly square to a seated sightline.

The default for any desk where surface is genuinely scarce.

Pad: maximum footprint, maximum return

Only worth it if people write on the desk, because it becomes the writing surface.

Needs a stock that takes a pen without indenting through to next month.

Day block: a ritual

One page a day, which lives or dies on the grade of the padding adhesive.

Check the stand still holds the block when it is nearly finished.

Compact: for a desk that is not yours

Folds flat for a locker or a laptop sleeve, stands in one movement, no fixings.

The only format that survives a clear-desk policy.

And the refillable stand

Costs more in year one and less every year after. Buy it only for a programme.