The question assumes all humans and pets are already safe and out of the house.
I suppose we should have addressed which sentimental things would you take as it's far more interesting than important docs and hard discs!
I have a couple of boxes of 'stuff' dating back to god knows when, that just sit in a cupboard. Much like my many photo albums I only ever really look through when I move house - which used to be quite often, but I've been 5 years here now!
It contains a huge bundle of love letters from a Greek boyfriend.
A huge bundle of letters that I sent to my mum whilst I was travelling round Australia and NZ so kind of like a diary (tbh I've never reread them).
Plectrums from punk gigs I went to, plus song lists from said gigs which the bands had taped to the floor in front of them.
Old diaries from teenage years
Stamp book!!!
Autograph books including my grandma's one!
My old school reports are stuffed in the fireproof box with the important docs but my old school photos are in these boxes of 'stuff'.
I'd hate to lose these things!