A good quality wool blanket. I personally like Topsy Farms as a smaller, family owned company- I have 2 wool blankets from them that are about 20 years old now. I also have a Hudson Bay blanket that's older than me as well.
I recently got an alpaca throw blanket from AppalachainGearCompany that is a bit lighter weight but so far is great when I just need a little something. I can't say for sure it's a BIFL but so far it seems good quality.

I have a handmade corn-broom with apple tree handle that's been in service for 18 years currently. Made by Sam Moyer in Southampton NJ. I also have two hearth brooms that are same age.