Which is the best loader in Three.js?

I want to do some operation on 3d external file. for example I want to read file x y z axis, I want to restrict or set boundary on that 3d file. Which is the best loader to do operations.

This post might help you to get a first overview of formats and loaders:

Furthermore, i’m not sure i have understood your requirements. You need to describe more precisely what you actually want to do.