STEP 1) Audience & Intention
Is this drum for you or a gift? If you are purchasing a drum for a young child, I would recommend either the 6" Bella or 8" Lunabell. Seasoned musicians might prefer the 12" Domina, a balance between travel ready and impactful acoustics. The 14" Dominus and Dual Tone are better suited for studio staples. All sizes carry beautiful melody that is easy to get lost in, no matter the skill level.
STEP 2) Color
Every size has it's own unique color variance. While some popular colors, like Sapphire Blue, are available in every size, some models are limited. The 8" and 12" Blue Lotus Chakra Tuning tongue drums
are a examples of some rare Idiopans worth adding to your collection. They are especially unique because they come with the advanced magnet pack.
STEP 3) Accessorize
To pick-up or not to pick up, that is the question. The smaller sizes carry well, but I would recommend sizing up to 12" before investing in a pick-up.
One of the coolest parts of this option is the ability to add effects via pedals and programs.
I am not personally a tech oriented musician, but I could see myself learning more with Idiopan. For advanced musicians, I would definitely recommend the magnet pack mentioned above. You can get an even greater variety of tuning options.