I'm looking for a Wifi Access Point that's supported by Openwrt. I want to provide a least two different Wifi networks. The device should also support VLANs for that purpose.
On the ethernet site the speed should 1GBit/s. On the wifi side the device should support at least 802.11n.
The memory size should be big enough for using the device several years.
Yep. I have a WRT32X, which I think is the same HW as a WRT3200ACM that is running multiple wifi networks and VLANs. Also have an older WRT1900acs that does the same. I am also trunking the VLANs over a couple other routers so the APs have the same VLANs. Most semi-decent routers even older ones support VLANs.
What are the benefits of David's build except an updated driver and some preinstalled packages? I'm looking only for a Wifi access point (especially for the guest network). All other services (file server, firewall) are already provided by other devices.
You got the benefits of those builds. FWIW I am running the 18.06.1 release build a WRT32X that is my main router. I have one of David's builds on a WRT1900ACS that I use as an AP. Has a lot of pre-installed packages, but to your point no significant difference other than that. I haven't seen a need to reflash the WRT32X from release.