Topmararis it seems that you have been sucked in to the world of Fanbois. For every AMD fanboy that calls someone a Nvidia shill, there is someone in the Nvidia camp bashing people from AMD. So you have to be careful where you get your info from.
As to your issue with crossfire, I have seen all over the web people have issues with crossfire either on a per game basis or generally. However there are other people who have no issues with it. The same can be said for Nvidia SLI tech but admittedly to a lesser extent.
I am not sure if you did a clean install of OS and/or completely removed the Nvidia drivers from your machine but reviewers usually run benches from a clean install so they are less likely to have issues that the general public experiences.
One GPU tends to run better than two and I don't think SLI/Crossfire is a bullet proof solution on an open platform such as the PC seeing that there are variables such as how much time devs will invest in making them work or if they game is developed from the ground up to work best with just one vendor.
In a closed system it multi GPU works just fine. An example of this is PS4 Pro which is essentially 2 GPUs crossfired.
For your needs I would recommend a 1070 or something of the sort for your next GFX card. Personally my next upgrade will be something that can do about 30fps at 4K and use the down sampling feature to run it with more fidelity on my 1080p screen.