[Build Help] Need advice on which to part to upgrade first

Hello there,

Sorry in advance if my format is ugly.

So I haven't upgraded my PC for a while and now I'm debating on buying a few components for it. However, I'm on a very small budget due to.. reasons (no job QQ). I would like to do an overall upgrade in the long run, but as it stands right now; I can only buy a GPU or processor/mobo+RAM. My current specs are as follows:

• i5 760 overclocked to 4.01GHz

• Asus P7P55D-E Pro (talk about hold huh)

• EVGA GTX 770 2GB

I am debating on upgrading the GPU first to a MSI 970 Gaming 4G(or something else if you can provide any alternatives) OR upgrade my CPU/Motherboard to an i5 6600k/MSI Z170A Gaming M5

The recent Open Beta for The Division showed me that my rig is still capable of living for a while (was able to uphold medium/high settings above 30FPS) but I feel like an upgrade is needed.

P.S I live in Canada so prices are very different than in the US.

Edit: some words