Collingwood would prefer to see Finn in the lineup because of the "X factor" he brings on dry wickets ahead of Durham teammate Onions, who along with the Middlesex paceman is in the fight for the final starting place.
Collingwood told Sky Sports News: "I know what Graham Onions can do, especially on seaming wickets but if it's going to be dry Finn is the man.
"He has got that extra pace on real flat wickets and he can give you something really special with the pace and bounce that he brings.
"I know the Australian batsman feared him, he was fantastic against them in the one-day series last year, he's got something special about him, he's got the X factor."
Finn took three wickets in England's warm-up game against Essex earlier this week.