From what I know, Kasina practice involves visualising certain simple shapes or objects such as candle flames and coloured disks.
Tibetan Buddhist practices involve visualisation of fairly complex 'deities'; supernatural beings wearing certain clothes, certain ornaments, surrounded by certain other complex objects. As the visual complexity of the imagined scene is much more than in Kasina practice, the 'phantastic' benefits might be different as well. The deities are convenient as visual object because (I suppose) Tibetans are familiar with their visual appearance. Choosing any other similarly complex familiar object should work as well.
Ingram described Kasina as gradually increasing the complexity of the images, after success with simple ones. But I confess I don't really know much about this.
Tibetan Buddhist practices involve visualisation of fairly complex 'deities'; supernatural beings wearing certain clothes, certain ornaments, surrounded by certain other complex objects. As the visual complexity of the imagined scene is much more than in Kasina practice, the 'phantastic' benefits might be different as well. The deities are convenient as visual object because (I suppose) Tibetans are familiar with their visual appearance. Choosing any other similarly complex familiar object should work as well.