In Mathigon you can ask and answer questions and share your experience with others!
So many great ones to choose from, but I'd say my current favorite are the Prime Factor Circles. It's so powerful for students to be able to pull apart and then combine together again individual prime factors. So many great uses for these!
I got a lot of milage out to the fraction tools with my grades 3-5 teachers last year.
I love that I can make high quality graphics, which can be dowloaded as .pngs and then inserted into any jamboard, google doc, slidedeck, etc. without breaking copyright laws or having to get someone's permission to use their graphic! The green flex tool under "tiles" is so versatile. I love that the images can be made on a variety of backgrounds, or no background and that I can shade the images with lots of hues and even transparencies. Here's an example of a simple triangular prism25 I made to scale using polypad.
It's so tough to choose, but I would choose the custom polygon. The ability to make any polygon you want and re-size, makes it so flexible! I also like @David Poras11's idea to make your own tangram with the custom polygon.
