Rasberry pi 4 is based on Broadcom BCM2711. Broadcom BCM2711 has advanced ARM-A72 achitecture. New architecture is the main distinction of 4-th version of Raspberry Pi in contrast with 3-rd version (ARM Cortex-A53).
There are not more chipsets provides ARM-A72 and having single boards based on them with competitive price. Still they are present. So let's review it.
The main Rasberry pi 4 rivals are RK3399 based SBCs.
RK3399 SOC has 2x2.0GHz Cortex-A72 + 4x1.5GHz Cortex-A53 64-bit CPU and Mali-T864 GPU (OpenGL ES1.1/2.0/3.0/3.1, OpenCL, DX11)
We give you distinctive characteristics of the most popular SBCs in the table below (more detailed comparison). All presented models has build in WiFi module(except ROCKPro64), Ethernet 1Gb, USB 3.0 interface and eMMC(empty slot or build in).
| Rock Pi 4 (by Radxa) (≈ 75$ for 4GB RAM ver. + 8$ M.2 extansion board)
It has relatively small size 85mm×54mm which is almost equal to Raspberry Pi 3 Model B+ size.
Rock Pi 4 is equipped with M.2 SSD interface(over extension board).
(≈ 80$ for 4GB RAM ver.)
This SBC has PCIe 4x interface, which is more specific for traditional PC. So you can plug a wide range of devices for PC, but you still can plug M.2 SSD over special adapter. It does't have a built in WiFi module.
| Orange Pi RK3399 (≈ 105$ for 4GB RAM ver.)
Orange Pi RK3399 is rich in interfaces. There are miniPCIe(for LTE/mSATA), SIM slot to use as LTE module for miniPCIe extension, mSATA interface and other familiar interfaces.
| Nanopc T4 4Gb (≈ 110$ for 4GB RAM ver.)
It has M.2 M Key (NVME PCIe x4) interface.
(≈ 139$ for 4GB RAM ver.)
It is one of the 96Boards. So it has standard 96Boards CE form factor.
As for distinctive interfaces, it has 4 lane M.2 PCI-E 2.1 interface.
| Khadas EDGE-V (≈ 160$ for 4GB RAM ver.)
Khadas manufacturer proved itself with good software support. EDGE-V has M.2 Socket 4 full-duplex lane PCIe 2.1 (M.2 2280 NVMe).