Tido, I would say Armbian Jessie (just what you said) and OpenWRT. OpenWRT is ideal if you want a quick working router os. Armbian Jessie is more for if you want to configure and maintain it by yourself. Plus the links you provided are not working any more, I put a link to the image here (Last official Armbian (Jessie) Lamobo/Banana Pi R1 - EoS (End of Support)).
I recently tested the official debian 10 and sid. Installed using the debian installer from the official site. It worked perfectly, without failures and reboots for more than a month. In router mode with wireguard VPN and wi-fi access point. Recommend. The installer allows you to install the system directly on the sata disk, on the SD card only the bootloader.