This depends on one big thing-how much you take care of it. But let's break it down: If you treat 'em right, both last a long time, but stainless steel is a little more forgiving.
Carbon steel? I've had mine for 3 years, and it's still going strong. But here's the catch-you gotta dry it after every use, oil it sometimes, and fix rust spots fast. If you leave it damp or let rust sit, it'll wear out quicker. My cousin forgot to dry his once, left it in a wet toolbox-rusted so bad the blade got pitted, had to replace it after a year.
Stainless steel? It's more low-maintenance. You can leave it a little damp, and it won't rust right away. My neighbor has a stainless steel one he's had for 5 years-never oiled it, just wipes it off sometimes, and it still works. But here's the trade-off: Stainless steel dulls faster than carbon steel. If you use it a lot, you'll sharpen it more, and over time, that can wear down the blade.
Me? I prefer carbon steel 'cause it stays sharp longer, and I don't mind the extra care. But if you're forgetful or don't wanna mess with oiling, stainless steel might last longer for you. At the end of the day, both can last 3-5+ years-just depends on how you treat 'em. I've seen people use carbon steel knives for 10 years with good care, so it's totally doable.
