Which of the following is right in this context?
Who is your favourite footballer and cricketer?
Who are your favourite footballer and cricketer?
Which of the following is right in this context?
Who is your favourite footballer and cricketer?
Who are your favourite footballer and cricketer?
Well, if you were curious what combined footballer-cricketer your friend liked, you would say "Who is".
If you were allowing that the favorite footballer and the favorite cricketer might be two different people, then you would use "Who are".
As a native BrE speaker, "Who are your favourite footballer..." just sounds wrong, because "are" is plural and "footballer" is singular.
"Who is your favourite footballer and cricketer?" is a perfectly good abbreviation of "Who is your favourite footballer and who is your favourite cricketer?" - which is too long-winded and pedantic to ever be used in practice.
"Who" can either be singular or plural.
Who is your favourite footballer and cricketer? (Who is singular) - In this case is refers to one person. This gives a sense that the person you are speaking of is both a footballer and a cricketer. In other words:
Who are your favourite footballer and cricketer? (Who is plural) - Here are refers to more than one person. This tells us that a footballer is one person while a cricketer is another one. In other words this means:
Edit: I was perhaps technically wrong, but I would violently reject the "correct" grammar as well, so it is perhaps better expressed as:
Who is your favourite footballer? And cricketer?
or
Who is your favourite footballer? And who is your favourite cricketer?
If you think about it from a Latin perspective, "is" is singular in form, which means "is" is used for one thing. "Are" is plural in form, so if you are talking about two people, then use "are."
For what you have, I think it should be:
Who is your favorite footballer and cricketer?
However I feel like this sounds better:
Who are your favorite footballers and cricketers?