Alright, I ordered Module, Spiral, and Polygon earlier last week and I have tried them all. (So, now I have 4 Tenga 3D - Pile, Module, Spiral, and Polygon)
I guess I can do a little bit comparison.
As to the level of how intense the sensation is, I would rate: (1 - most intense)
1 - Pile
2 - Spiral
3 - Module
4 - Polygon
I am sure that the texture of Pile gives you the most intense sensation among all other Tenga 3D. (For me, it is too strong and I lost control so easily.) Although Spiral and Module are not as intense as Pile, they still give you quite strong sensation. Also, they are very close to each other, in terms of level of how intense the sensation is, but in different texture. (But I would rate Spiral a little bit higher over Module.) Polygon is much more gentle and smooth, compared to the other three. It is easier to manage and still gives you some pleasure.
So far I like Polygon more than the other three.
I hope this will help you decide which one to buy.