I used to use a British army black plastic canteen then an aluminium canteen, but have now got a boundless voyage titanium canteen with cookset, a 1.2l titanium bottle and a mill bank bag and ceramic filter system ( I usually get water from springs on Dartmoor but still filter them, 'just in case') I find the lightweight titanium is great, it is seriously lighter than both the plastic and aluminium ones, is strong, rust resistant and chemical resistant ( good for when I occasionally use purification tabs) . I admit they were costly in comparison to the plastic and aluminium canteens, but I personally feel that hiking and travel with less weight to be worth the extra costs. Plus there are 'leaching' issues with plastics and aluminium, none with titanium.