A question about RAM

I currently have 8GB Corsair Vengeance Pro (2 x 4GB) DDR3-2133 RAM. I am thinking of adding another 8GB because my ram usage is usually around 85% when playing games, 60% when just on the internet.

My main question is, should I get the exact same RAM again for my system? or should I go for faster RAM like this: Corsair CMK8GX4M2B3000C15 Vengeance LPX 8GB (2x4GB) DDR4 3000Mhz (https://www.amazon.co.uk/dp/B0123ZBPDA/ref=twister_B01MXL531D?th=1) Sound dumb asking that question but it has been a while since I upgraded my build.