What are some alternatives?
When comparing Wintersmith and Nikola, you can also consider the following products
GatsbyJS - Blazing-fast static site generator for React
Metalsmith - An extremely simple, pluggable static site generator.
Hexo - A fast, simple & powerful blog framework, powered by Node.js
Assemble - The static site generator for Node.js, Grunt.js and Yeoman
Jekyll - Jekyll is a simple, blog aware, static site generator.
Nanoc - A static-site generator written in Ruby