On paper, the AOC is an IPS panel compared to the TN on the Iiyama, so the AOC would be brighter crisper colours, the downside of IPS is a slower response time of 5ms vs 1ms.
I moved to IPS on my last monitor upgrade from a TN and I can't notice any blurring due to the slower response rate, BUT, my eye isn't that keen, must stress that. On paper, I'd go with the AOC, but I'd still choose the Iiyama as I've had a few of them and they've always been excellent panels.