Typically, a portrait needs to show catchlights in the eyes.
Those little sparkles of light. Like in this portrait of a recent client, Mo Vikrant, an amazing (and amazingly well educated) young financial advisor in Toronto:
Can you see how those dots of light add life, add sparkle, to this portrait?
Now, I am not as adamant as PPOC, the Professional Photographers of Canada, that every eye must have a catchlight (and only one), or it is a failed portrait. But I do think that typically, yes, they need to be there, and they need to be round.
So I used a speedlight shot through (not reflected off) a partially-unfurled umbrella for that portrait.I cold also have used the Honl Traveller 8 softbox – this too would have given me nice round catchlights.
Detail is important!