When comparing Blocks.js vs CanJS, the Slant community recommends Blocks.js for most people. In the question“What are the best JavaScript libraries for building a UI?” Blocks.js is ranked 10th while CanJS is ranked 12th. The most important reason people chose Blocks.js is:
Blocks.js is just 16.5KB minified and gzipped. So it's pretty small.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Small footprint
Blocks.js is just 16.5KB minified and gzipped. So it's pretty small.
Pro Modular structure
Apps developed with blocks.js are modular in structure and make use of reusable objects. This makes these applications very maintainable.
Pro Great browser support
CanJS supports all modern browsers and IE9+.
Pro CanJS can be used with any other library
CanJS is a collection of individual libraries, each separately available as npm packages. It's easy to use just what you need.
Pro Real time support
CanJS's model layer (can-connect), support real-time updates to lists without adding any additional code.
Cons
Con Relatively new
Blocks.js is a relatively new library. It doesn't have much support and there re not many people who use it. So if you run into any problems it would be hard to get solutions.