Thank you for the detailed response. I really appreciate it.@Squuiid the only thing I've noticed is that Voxel uses a slightly dated UI, but beyond that, I have not seen anything that would be negative over the stock firmware.
Keep in mind that it's very hard to do anything to the Wi-Fi performance, as that tends to depend a lot on binary blobs that are provided by the chipset maker. These are rarely updated by the router manufacturers, unless there's some major changes/fixes that they have to add to their products.
Having worked for a router manufacturer, I can tell you that all the router chipset manufacturers, i.e. QCA, Broadcomm, Realtek, MTK etc. are shirte when it comes to updating their software. MTK is afaik still not even on kernel 4.x for most of their hardware and the latest QCA 802.11ax SoCs are running kernel 4.4 or something along those lines. It's not easy to make some of the binary blobs provided by these companies to work with more recent kernels and sometimes it's not possible at all. As such, the updates that can be done, are in general optimisations of other bits of software on the router, as well as update things that can be patched easily when there's a new security update.
In other words, don't expect miracles from the likes of Voxel or Merlin, as their hands are tied when it comes to being able to update some parts of the router software.
I'm actually dismayed at how little the chipset companies cares about updating their software and to provide stable, modern software. However, they get away with it as none of the router manufacturers are requesting it. I guess this also comes down to the end customers not asking for, as most people are clueless when it comes to routers and more so about the importance of having secure and up to date software running on their router.