I think there is many posts about this but i can't find my favorite answer. i want to create new blog for an ecommerce site, i used joomla for many years and joomla is my first option to do that, but joomla does not has built in commenting system, so i decide to use K2, but last release of k2 is for 1-2 years ago, DOES k2 updates? will be ok with new releases of joomla?

and i shold use joomla's core articles instead of K2? or it is better to go with wordpress? ( i have not used wordpress before)

Κ2 will work with all major Joomla! version and it will continue to be updated.

Now, it the main site was build with Joomla! then the blog should be done with K2. Otherwise you can look into the CMS that you are using blogging functionality.