My list would be difficult to whittle down: A Singer manufactured govt 45 from WWI, an original Single Action Army, the rifle Cpl Alvin York used to subdue over a hundred enemy soldiers, Peter Capstick's .375 H&H that he talks about in Death in the Long Grass.
I have to say that sentimentality wins out for me. I'd want my mom's Savage 250-3000 that dad bought her just after they were married. She gave it to me but someone else decided that they need it more than I did and stole it from me.