As an agility prospect, I would be looking for the outgoing one, the one that wants to play. However, I would also look at a dogs work ethic. One that will try new things without pitching an overly large fit, learns quickly, and will do things because you asked are things I want in my agility dog. Also, a dog who is extremely noise sensitive can be tougher to have for agility. It also doesn't hurt to have drive. I test my puppies by trying them on puppy-size contact equipment/tunnels, leash training, and teaching basic obedience. It lets me learn a lot about their personality, what type of dog they're going to be, and what they're suited best for. A dog who is willing to work for you will make up for a lot.
As for the dog being a velcro dog, be careful what you wish for, and really think about what type of dog you want on the agility course. I have both types- velcro dogs, and those who like to work at a distance. They are completely different to run. My velcro dogs tend to be very handler focused, and are generally very accurate. However, it can be difficult to be where you need to if they're stuck to your hip, and you're going to wind up doing a lot more running because you'll have to run along with them. My distance dogs are usually more independant, and I can get great send outs on them, which makes it easier to be where I need to. I also don't have to run quite as much with that type of dog. These also tend to be my faster dogs because they aren't worried about being stuck by my side. There are pros and cons to each type.
If you're serious about the agility bit, and it's not going to just be a casual once in a while thing, I'd look closer at the girl.