I have never fly sparged. Up until a few days ago, I didn't have any equipment capable of doing so, and even with the new equipment I still don't think I will do it. I don't know why... maybe the extra water in the mash tun creating a more difficult cleanup, or trying to time the water in vs. water out... I just don't want to do it. That being said, even with batch sparging I still mash out, but I also have heard it may not even be necessary
If someone told me that fly sparging was better than batch, I would probably go for it. But everyone seems to differ in opinion. Some say they think fly is better, most say it doesn't make a difference (at least in home brewing).