You can use either cable but USB 3.0 will charge significantly faster when connected to a computer USB 3.0. It won't make a difference if using the wall charger as long as the USB 2.0 has a proper rating.
It might charge faster but when I connected my note 3 using the stock cable to a USB 3.0 port in my computer , I didn't notice any quicker charging. Theoretically you can see up to 900ma on a USB 3.0 port, but the stock charger is 2a anyway so computer charging would most likely be slower than wall outlet.
dpham00, Android Central Moderator
Sent from my Verizon Samsung Galaxy Note 3