FreeRTOS on STM32 - What API should be used: CMSIS-RTOS API (v1 or v2) or FreeRTOS API?
This is almost 100% opinion based answer. I personally do not like CMSIS wrappers. There is to much silly (IMO) macros and hidden objects created by them. I actually prefere freeRTOS API if I use freeRTOS.

It makes also debugging more difficult.