Christmas pudding by a mile! With brandy butter.
I make my puds, though - not keen on shop ones - too dark, dense and heavy. I use an old GH recipe - people who don’t usually like Christmas pud often like it - but I always say nobody must ever feel obliged to have any - it’s such a waste, giving it to people who don’t really like it.
Dh and I will often be eating the 2nd one well into January.
I’ve never bought panettone. We were once given one, and TBH it was very dry and nothing to shout about at all - most of it ended up on the bird table.