gstoyanov

espressoBIN is a decent choice - good performance at a decent price, and a community here on Armbian that can support it
 
The ClearFogs are a step up, even though their on an older ARMv7A Armada - the 8K is newer and is ARMv8, but not sure where the BSP support is there.
 
There's been a trio of QC-Atheros IPQ-40xx devices recently announced, and they have integrated 802.11ac dual band radios - but most of them are somewhat tight - e.g. to get best performance out of them, one has to use the QSDK, which is built on an older version of OpenWRT - there is support for some IPQ40xx in OpenWRT 18.06 and Master, but I'm not sure it's stable enough yet for daily-driver use on the WiFi (ath10k drivers are under heavy development, and there's issues with the Switch outside of typical setup - see DSA on this chip over on OpenWRT forums...)
 
I was starting to develop a fairly open board based on AR9331/AR9531 - not ARM based, as these are MIPS cores, but the SOC is very well documented, and strong OpenWRT support, but that got set aside when work stepped up and my free time was reduced quite a bit.

I think you need to decide if you are doing this to save money or doing this to build something and gain learning experience.  If money is your goal, you will almost certainly be better off buying an off the shelf access point.  If you want to build something, just realize it will cost more and likely not perform nearly as well.  Here are a few suggestions though in no particular order:
 
1.  Espressobin v7  - $69 - new versions does have ddr4.  This might be your best option as you can also get this $20 wireless card that fits in it:  https://www.globalscaletechnologies.com/p-81-marvell-88w8997-2x2-wi-fi-80211acbt-50-minipci-card-20.aspx 
 
2.   Clearfog Base - $120  https://www.solid-run.com/product/SRM6828S00D01GE008B01CH/
 
3.  Clearfog 8k - $220 - https://www.solid-run.com/product/SRM8040S64D00GE008V11GH/
 
Anything from Solidrun as mentioned in the comment above.  Also, do you really only need 1 eth port?  If so I would say that expands your options quite a bit.  But then you are really talking less about a router and more like an access point.

With a reason. "Supported" is when certain/good software maturity is achieved - if you are not a kernel hacker and developing low level support is your goal/wish, stay away from those boards due to extremely bad software support. Choose only among "supported" - even there problems are present, but they are usually minor/acceptable. If you can wait, pay attention on WIP. Most of them usually become "supported", but some are also dropped ... if we find out a huge investment is needed. We have no full-time developers and virtually no budget for R&D.