BIOS OC'ing is always more accurate/granular, and would be my recommendation.
Saying that, using software can give you a very loose, general idea of what you can expect - they do tend to overvolt in my experience though.
For example, if Ryzen Master suggests 3.9GHz @ 1.35v (hypothetically), you can usually expect to achieve the same clock speeds with a little lesser voltage, with some fine-tuning.