How to decide to create a multilingual site or to create different site for each language? This is the first time I want to create a multilingual website. The site is Turkish now and I want to add English as second language (for both interface and content).

The main site (the Turkish one) has about 15 content types and each content type has 10-20 fields (text, entity reference, date, image etc). Also each content type has its own node.tpl.php and I made lots of customization to display node types. In short, the site is a bit complex.

I made some research about creating multilingual site (in Drupal of course) but I couldn't decide yet to use Drupal's multilingual features or to clone the Turkish site and create another site for English with some (language) modifications.

Creating two separate site is easier for me but using Drupal's multilingual features seems the "correct" way but more painful.

How to decide to create a multilingual site or to create different site for each language?

(More details: - Almost all of the contents in the Turkish site will have its corresponding content in the English site. - There is a team of non technical editors.)
In my personal view, I will consider if the new language site will be mostly identical to the existing one or not.

It means that if most of the pages / contents in the Turkish site will have its corresponding page / content in the English site, then I will build multilingual site, otherwise, I would like to set up a separate one.