My house is in the woods and after years of trying everything else I have the surface tension type.
Gutter Helmet Surface Tension - YouTube
They aren't perfect. They needed to be cleaned once a year, but that just means scrubbing the edge the water runs over with soap and water. I was skeptical at first and the salesman told me they were guaranteed. I said, "Guaranteed to work?" and he grinned and said, "Guaranteed to be made out of high quality aluminum." I got a functionality guarantee from him and went with it. It's been about 10 years and I'm happy with them. I can't remember what they cost.