Should I go for Drupal7 or Drupal8?
Drupal 8 is a better platform , it has a better structure , more features in core , it is based on symphony2 and so the module development is different from what you knew in drupal 7. template engine also is changed to twig so again you have to change your point of view about how used to theme before .

Another thing must be mentioned before making your decision is that there are too many module for drupal 7 and you can find a module for almost any job but cause drupal 8 is new , many modules are not still developed for this version.

All in all I should suggest you that it is a good idea to migrate to drupal 8 but if you have a deadline for your project this may not be a good decision to start it with drupal 8 ,cause it will take some times to be adopted.