I would prefer the leather ones but find the grasmeres plenty warm enough and get more wear out of them than I would glaciers - they'd be too hot a lot of the time!
I have just bought the grassmeres purely because I prefer the look of them. Lovely boots but haven't really had them long enough to know how they will wear.
I have the Glaciers and LOVE them, I have really cold extremities and these are a god send! I muck out, trudge through deep mud, ride and generally hammer them and while they look tired they are still going strong 7 years later! Very impressed with them