Geralt Igni and Professional requires setup, while Rivia and Leo does not. Yennefer is an alternative, to place the unit on top of the deck of the owner, in case needed. And it seems like a pretty good alternative if you combine it with Cantarella.Leo and Geralt can sometimes brick since they won't find a target of 8 or more power while Professional is always at least 6 points. Every point counts! I like running Nilfgaardian Knights to boost enemy units so that its easier for those cards to get value.
I bring Leo or Geralt as a technical card to take out any unit above 8 with no setup or complications. Strangely Leo is better since he can also take out any witcher in addition/instead, and thus bricks less often.
I've seen alot of people bring professional, and I understand why they do that. But without a control type deck with alot of different damage, or even some boost, it seems less valuable to me than Rivia and Leo who are just plain and simple.