When comparing Learn Python the Hard way vs CheckiO, the Slant community recommends Learn Python the Hard way for most people. In the question“What are the best resources to learn Python?” Learn Python the Hard way is ranked 3rd while CheckiO is ranked 18th. The most important reason people chose Learn Python the Hard way is:
Teaches by giving a piece of code and letting the user see what the code does.
Ranked in these QuestionsQuestion Ranking
Pros
Pro Practical
Teaches by giving a piece of code and letting the user see what the code does.
Pro Free
Available online for free.
Pro Encourages use of flash cards
To help better remember certain parts of the language, the author suggests using flash cards.

Pro Community backed solution reviews
Users can publish their solutions for different problems and other users can review the code and give their opinions on how they would have solved the problem.
Sometimes, some of the most active users get their code reviewed by Guido Van Rossum (the creator of the Python language) himself.
Pro Available in multiple languages
CheckiO crowdsources translations for problems. Currently problems have been translated in 10 languages. So it's highly possible that eventually more languages will be supported.

Pro Ability to create new challenges
New missions can be created and uploaded using GitHub. After that is done, it's suggested to CheckiO and if it fills all the requirements after being reviewed by a CheckiO team member, it's pulled into the game.

Pro Challenges from GitHub, O'Reilly, Dropbox and Hubspot.
Cons
Con Author still suggests newcomers to the language learn Python 2
The only reason to learn Python 2 these days is if you have to workout on legacy Python 2 software, and upgrading to Python 3 is not an option. Telling newcomers to learn a outdated, and soon to be unsupported version of the language is detrimental.
Con Suggests looking up details on the web
The book often suggests looking up details on the web instead of providing them. Additionally, no resources are suggested where to look up such information. As a result the quality of explanation of details can vary based on used resource.
Con Not for absolute beginners
CheckiO does not teach syntax, instead it teaches how to solve problems using a particular programming language therefore some basic programming knowledge is required to start.
