It all depends what you are planning to do with the space.
If it is just to be attic space with no access, then quilt is a suitable solution (250mm~280mm thick).
If you need access quilt would be suitable again, but you would need to put counter battens to raise the floor above quilt level.
If you are converting the loft insulation is normally provided between the rafters which, is normally a rigid foam board.
There are a number manufactures in the market and they all provide U-Value data, we have no preference as to any one supplier providing the U-Value is met and ventilation requirements are satisfied.
