An AIO board can make a compact build simpler because several functions are combined on one PCB, often reducing wiring and weight. The trade-off is that a failure in one integrated section may require replacing or repairing the whole board. Separate components can be easier to replace individually and may offer more flexibility for higher-power builds. The right choice depends on the frame, battery configuration, expected current, and space available. You can compare different flight electronics here: Check the rated voltage and current carefully, rather than choosing based on board size alone.