ESP32 with external stepper drivers or BTT controller board with internal steppers for DIY CNC?

CNC noob here, planning to build my own from a mini mill and run GRBLHal. Trying to keep things cost effective and buying a Bigtreetech SKR Mini board is cheaper than getting an ESP32 and three external stepper drivers. Is there any advantage to going the external driver route? If it provides a better learning experience that could sway my decision as well.