Ranked in these QuestionsQuestion Ranking
Pro Registry agnostic
JSPM is registry agnostic, it can pull packages from npm and github and is built in such a way it can support more.
Pro Can transcompile ES6 and JSX
Pro Module style agnostic
Loads ES6, AMD, CommonJS and globals.
Pro Versioned package urls
It creates a packages folders which are versioned. This makes it future proof for a time where we stop bundling all the code. In the following presentation Guy Bedford calls bundling an anti-pattern.
Con Poor bundler performance
Bundling performance is slow, though offset by the fact that bundling is not required during development, since it can load dependencies asynchronously.