When comparing NanoPi M4 vs Rock64, the Slant community recommends Rock64 for most people. In the question“What are the best single-board computers?” Rock64 is ranked 9th while NanoPi M4 is ranked 59th.
Ranked in these QuestionsQuestion Ranking
Pro 6 core HexaCore, compact nvme extender, 4GB RAM
Pro Open Source
Works with mainline Linux kernel and open source Mesa Panfrost drivers.
Pro Many ports
4 x USB3
2 x USB2 available via pins
PCI-E available via pins
Rockchip 3399 with two fast A72 cores. Good heatsink limites throttling.
Pro USB 3 Bus support
Pro Can have up to 4gb of low power RAM
Pro Gigabyte ethernet
Pro Beats Raspberry Pi on price and performance
Pro Main header Pi 3 pin layout
Can use Pi shields.
Pro 4K/60h hdmi 2a
Pro Barrel power connector
More rugged connection. Less likely to be damaged.
Pro Extra Gpio pins
Con Bleeding edge...
To have mainline kernel requires a bit of tinkering (e.g. installing Armbian). Panfrost drivers for 3d acceleration are not mature and crash sometimes...
Con Lack of support, Unstable USB 3,
Only Android with TV UI is available. It is almost unusable with a touchscreen display.
Community is somewhat helpful but is very small. The board developers do not participate in community discussions. No regular Android build available. Lack of accessories and project guidelines.
Con Power connector is not MicroUSB or MiniUSB
Can't use power banks as a power source because of that.