Wilton House, eh? I could have gone to this - Is it an annual event?
It was posted on here with plenty of notice. As for this being better than Goodwood. I assume you mean Breakfast Club and specifically Supercar Sunday, in which case I say possibly.
A lot of the cars you can see at both events with Goodwood being free to enter and food/drink available after a short wait.
The Wilton event is far grander than Goodwood but all done in the name of Charity which is good in itself. I personally think both can exist as a trip to Goodwood Breakfast Club doesn't last all day.