Transfer to Virgin Atlantic miles from which card?

Pointify is tracking this transfer bonus for the points-and-miles community.

I’m looking to book a flight and Virgin Atlantic seems to be the cheapest option with miles. Given there are no current transfer bonuses, which credit card should I transfer from? I have enough miles from Amex, Capital One and Chase but I’d like to transfer from whichever is the best value. I’m thinking Capital One. The flight is less than 4 weeks away so unsure if it’s safe to wait for a potential transfer bonuses.