If given the chance, I'll take both - the window seats on an aisle you get with some puddle jumpers or in the business class cabin.
8 hour international flight: if it's an overnight west to east, aisle so when I sleep, I can really sleep. Though once I hit 40, I stopped doing overnight flights in something that isn't a lie flat, as I basically lose an entire day if I don't arrive rested. If it's an east to west, aisle, because I'm drinking all the beverages the airlines offer. Oh, yeah, you do know that they usually offer alcohol in economy on international routes, right?