Since you're asking about one or the other I would take the Citroen as it will pay for itself inside an hour on any of the 650pp races currently on the go..
If you're saving up for a C20,000,000 historic car then get the Jaguar as it will win those same races easily regardless of the cars that are fielded...👍
ps-forgot that you can win it in the Indy 500 A-spec. I've been buying so many of them lately for painting.