For years I use either Ernie Ball Regular Slinky 45 - 105 or D'addario XL170 nickel 45 - 105. I still use the two but could never determine which strings last the longest. I play 5 nights a week, at least 5-6 hours a night. What's your opinion on which strings last the longest? As far as tone, I could never distinguish between the two. I don't have a schedule as to when I need to change strings. I change them when they sound dead and there are many variables as to when and how they reach that point. I've never actually monitored they're life....hence, this query.