I'm still gonna go with the washing machine. Ever since watching "Victorian House" -- one of those PBS shows where they make modern people live like back in the day -- and its 13-hr weekly "wash day," which included boiling all of the household's clothes/linens in a large vat with various chemicals to remove all the soot stains from the charcoal fires. I mean, my grandma had one of those wring washers, and that's one thing, but using a giant wooden paddle to stir a vat full of boiling crap for hours at a time? No thank you.
For safety/health, I'd go with the fridge/freezer (not being a fan of salmonella, after all). But if I had to choose between Victorian laundry day and daily food shopping and cooking, yeah, no contest.
Actually, overall, probably the modern sewer-and-water system. Fresh, clean, delicious, safe water delivered to 15+ locations within my very own house? And our nasty stuff just whooshed away down the drain? Yes please.
I think my grandmother would have chosen wall-to-wall carpeting. She lived in Kansas with hardwood floors and a beeswax finish and three young boys, and four hours every Saturday was spent on hands and knees scrubbing and polishing. She thought carpet and a vacuum cleaner was the greatest thing since sliced bread (and probably then some).
