You can try using Views Tree module..

Project page says

Views Tree module provides a tree-based style plugin for Views. It is equivalent to the tree-based style template from Views 1.

It is based off of the list style. Although it generates a nested view, there is still only a single query run for the view making it quite performant.

For node count, you can implement same using views.. Check this post Views and node count for taxonomy terms..

You can try using Views Tree module..

Project page says

Views Tree module provides a tree-based style plugin for Views. It is equivalent to the tree-based style template from Views 1.

It is based off of the list style. Although it generates a nested view, there is still only a single query run for the view making it quite performant.

For node count, you can implement same using views.. Check this post Views and node count for taxonomy terms..