If you haven't already, I recommend you read The China Study. They've been studying diet for decades in countries with fewer diseases and less obesity. Eating animal products is very strongly linked to a variety of cancers, heart disease, osteoporosis, high blood pressure, high cholesterol, autoimmune diseases, diabetes, and much more. It simply isn't healthy.
Add that to the inhumanity and tremendous negative environmental impact of factory farming, and you've got a really good argument.
Wheresoever you go, go with all your heart. -Confucius