I used the Scottish Figures In Comfort bags and storage boxes. They were size compatible with the old GW cases.
I did buy two of the new Figures In Comfort Really Useful Boxes with inserts at Colours last year.
Four layers in a 9 litre box.
I do have three of the small plastic boxes, which are great for small teams.
They are suitable for larger figures (this box normally holds my Malifaux Perdita crew).
I am not sure which of the plastic boxes are still available under the new management.