This is a hard one to answer, because different situations call for different responses. If I have the chance to flee, I will. As a woman who has experienced her own weakness in the face of opposition, I feel that it's smarter for me to avoid conflict if I can. But if I'm cornered, I'm more than ready to fight tooth and nail. I have a similar story to yours: I was outside with my dog, an un-neutered male pit bull, when another un-neutered male bulldog came up. This dog had been coming around bothering us for weeks, and I always was able to chase him off before. But this time he'd sneaked around and appeared out from nowhere and immediately came for my dog. A fight broke out that would make a lot of people either run for cover or stand there and watch the horror unfold. But something took over in me, and I grabbed a big stick and started yelling and beating at both dogs, trying to wedge the stick between them to pry them apart. Thankfully, my dog got the invader by the ear and pinned him, and things were quiet enough for a moment for me to tell him to let go and go inside. (Pit bulls are actually excellent in these situations... they were originally bred to be responsive to humans when in the heat of battle, as was necessary for fighting dogs.) He obeyed, and I tried to chase the other dog off. He was shamed from his defeat, but still growled at me as I yelled at him. He was big. I was scared. But I knew that if I backed down now I would be toast. So I ran at him, cussing and waving the stick, and he ran off, never to return again.
So.... long story short, I would say that flight is preferable when applicable, but the ability to fight when situation dictates is necessary. I know my story didn't involve me actually fighting, but I do practice with my husband almost every day. He's into Judo and Kung fu and Krav Maga and all kinds of stuff, so he trains me rather effectively. It helps me feel more confident in my ability to defend myself, but it also shows me how weak I really am against men who may do me harm. So yeah. Run first. Fight if you have to. Never freeze up.