I've done some googling and I've narrowed down to the following. Keen for other monitor suggestions if I missed any and if anyone owns one of these please let me know your thoughts.
Essentially going to do gaming and work. I will have another 2 x 24 inch monitors on the side of this (I am a productivity freak). Keen to watch some youtube and netflix on 4K too. I feel 4K @ 100mhz to 120mhz is fine with me, I am not fussed with the newer versions of 4K @ 144mhz. Will be also doing PS4 Pro (in addition to PC) gaming.
So my shortlist:
Leaning towards Z35P due to the ability to OC to 120mhz. Prices for all 3 are pretty close, AOC is ~$100AUD cheaper than others, so price isn't that much of a big deal.