between ps3 and ps4 , if you want avoid lag take ps4

I started ps3, and upgrading to PS4 was a whole new world, able to see Odin , behemot and all the players

about upgrading to ps4 :

http://na.finalfantasyxiv.com/pr/ps4/ps3_users/

FINAL FANTASY XIV: A Realm Reborn PlayStation®4 Upgrade Campaign

Users currently playing FINAL FANTASY XIV: A Realm Reborn on PlayStation®3 are eligible to upgrade to the PlayStation®4 version starting April 11, 2014.

* Purchase of the PlayStation®4 version is not required to upgrade. Please be aware that after transferring to the PlayStation®4 you will be unable to play using your current copy of the PlayStation®3 version.
* Please note that after completion, the upgrade process cannot be undone.
Users may upgrade free of charge via the FINAL FANTASY XIV: Mog Station.
* Users must first register the PlayStation®3 version to their FINAL FANTASY XIV service account before upgrading.
* Upon completing the upgrade process, a PlayStation®4 system will be required to play FINAL FANTASY XIV: A Realm Reborn.
* All FINAL FANTASY XIV service account data including characters and in-game items will be carried over upon upgrading to the PlayStation®4 version.
* Users who wish to play on both the PlayStation®3 and PlayStation®4 must purchase a separate copy of FINAL FANTASY XIV: A Realm Reborn for the PlayStation®4.
* The upgrade campaign will be offered from April 11, 2014 until December 31, 2014.
I think the free month would be added to your account if you link a version to your existing account. But can't confirm.