Android TV box CPU
1) Most popular is Amlogic chips
S922X High end hex core, 4xA73 core +2xA53 core, upcoming, to compete with RK3399
S905X2, quad core A53, popular latest chip, mid end, USB 3.0 support and 4GB memory support. Eg: Beelink GT 1 Mini and Tanix TX5 Max. S905Y2 variant does not Ethernet
S912, mid end, 8 core A53, no USB 3.0 and up to 3GB memory. Eg: Minix NEO U9-H, Beelink GT1 Ultimate, Tanix TX92
S905X, mid end, quad core A53. Mi Box S (Android 8 ) uses S905X. Old Mi Box global version uses the same chip but comes with Android 6 and upgradable to Android 8. EVpad Plus has S905X CPU as well and with 2GB RAM and 16GB storage.
S905W, popular in low end, 4k 30fps support instead of 4k 60fps support in S905X, buy the 2GB RAM version and not the 1GB RAM version, usually comes with Android 7.1. Eg: Tanix TX3 Max and TX3 Mini
2) The other popular choice is Rockchip
RK3399 hex core 2xA72+2xA53, most powerful among the three vendors, performance only exceeded by the CPU used by Nvidia Shield TV. Overkill for TV box. Popular in Chromebook and high end maker boards
RK3328, popular mid end, quad core A53, performance similar to S905X, but with USB 3.0 support and 4GB memory support
RK3229, popular low end, quad core A7, performance below S905W, avoid them. Evpad Pro + and many preloaded box are using this chip.
RK3368 old mid-high end chip, 8 core A53
RK3288 old high end chip, quad core A17
3) Allwiner
H6, quad core A53, performance above S905X and RK3328 but below S912 and S905X2, USB 3.0 support. Usually comes with Android 7.x. Eg: Tanix TX6 (Android 7.1 and Android 9). Latest Ubox Pro 2 I950 comes with H6 CPU but RAM is only 1GB. Same for UBox Pro I900. EVpad 3 and 3Max use this CPU as well and with 2GB memory. EVpad 3S should be similar as well.
H5, quad core A53, seldom used
H3, quad core A7, Low end. Old Ubox Gen 2, 3 and 4. Evpad 2S+, Evpad Pro, Beelink X2, etc