Both are a problem. There is increasing evidence that eating meat causes many long term problems. (http://en.wikipedia.org/wiki/Red_meat#Health_risks) Additionally, see the news in the US in the past few days that supposedly ~50% of meat being currently sold in the US is contaminated (http://latimesblogs.latimes.com/dailydish/2011/04/gross-.htm...). And don't forget that raising animals for meat consumption is just terrible for the environment. I still eat meat, but I'm cutting way back and I feel really bad about it when I still do.

Perhaps you were just not getting enough protein in your vegan attempt? Or eating the right iron rich foods? One of my friends is a vegetarian, but he just eats pizza, pasta, and cheese and looks like a piece of giant dough. He's not doing it right and I wouldn't advocate anyone to follow his example. However, now is the best time to become a vegetarian or vegan. There are so many more non-animal protein sources available, it's unbelievable. It's not the 1960s anymore where you had to eat soy gruel.