A question ethics: animal welfare vs environmental concerns, which stand should you take?

Being vegetarian is far harder than I thought. It’s incredibly easy to do it half heartedly or hypocritically as I have discovered! Whilst sat in the park yesterday, eating my veggie sausage sandwich and feeling virtuous about my veggie efforts I rather naively was ranting about the mistreatment of animals whilst wearing leather shoes! Having looked into the alternatives to leather I have discovered that shoes marketed as vegetarian or vegan are made of cotton or faux leather. The environmental issues associated with cotton production are well documented (including the almost complete disappearance of the Aral Sea due to the use of water for crop irrigation) and faux leather is made of plastic. Call me cynical, but personally I think using one cow to feed several people and make many pairs of shoes is far better than producing plastic, a non-biodegradable substance formed from petrochemicals! The evils of oil are far more wide reaching including global economic instability from the price controls, pollution and destruction of fragile environments for oil extraction, not to mention the heinous nature of the Iraq war. Having said that, beef production in the past has been responsible for the destruction of rainforests for grazing land, global warming from the methane and, ultimately, obesity and heart disease! Maybe I should just stay barefoot instead.