From iPhone 4s to 6s -- how to transfer settings like mail accounts WiFi passcodes etc

I'm getting an iPhone 6s tomorrow .I'm using a 4s at the moment backed up on my computer.

Which is the best and easiest method to set up the new phone as far as Contacts calendars e-mail accounts

WiFi passwords etc. I don't care too much about music pictures or videos . I'm keeping the same

mobile number and carrier.