
As Apple introduced iCloud service in 2011, you can choose to transfer all the iPhone contacts through iCoud backup. If you don’t use iCloud or you haven’t created any iCloud backup, you can achieve so by using iTunes. If you haven’t created any iTunes backup either, you can export all the contacts information from the old iPhone directly and then transfer to the new iPhone 6s selectively. No matter you choose to transfer through iTunes or iCloud, you need to set up your new iPhone 6S by following setup directions to set it up at first. I am not gong to walk you through this process step by step, as you can find the detailed instructions at Apple Support Center.
I am going to introduce the way of transferring the contacts selectively from your old iPhone to the new one with third party software with by extracting the contacts from iTunes backup file. iFonebox is the software that can export the contacts selectively from your iTunes backup for your old iPhone and then transfer your contacts to your iPhone 6s.
You can download a free trial version of iFonebox to have a try and you need to pay for the full version if you wan to transfer all your contacts to iPhone 6s.
Below are the detailed steps.
Step 1: Install and get started the full version of iFonebox. Click to choose “Recover from iTunes Backup” to choose the recovery mode.

Step 2: An interface listing all the supported data categories will be presented to you. Please choose the Contacts to recover and export by clicking on the icon of Contacts.

Step 3: All the contacts will be exported, including the deleted contacts can be recovered. Preview all the exported and recovered contacts before recovering to iPhone 6S. Besides, you can do some modifications before clicking to transfer the contacts to iPhone 6S.

Step 4: Plugin your new iPhone 6S to your computer, and then click “Recover to Device” to transferring the contacts to your iPhone 6S.