You may already have left but I'd tell you a few things:
1. Much of the dogs you mentioned ARE herders (heelers, b. collies) and, as such, are going to be DRAWN more to 'herding' the ducks, chicks, etc. and which CAN cross the line into harassment really fast.
2. The most emphatic thing I'd tell you is do NOT go looking for a dog to bring home **today**. That's pressure on YOU to make a decision "gotta find one TODAY" -- and that will lead you to an unwise decision.
3. don't blame you for wanting a pup *however* I don't know you so I don't know your situation -- but is someone really home ALL the time to really train/supervise a pup? If you are wanting a dog to bond ***to YOU*** then if you leave Mom or a family member to have to do heavy duty 'training' like housetraining, then you actually diminish your own role. Does that make sense?
4. A thot for you: PA ranges from farm to big-time urban -- so I don't know what there is in terms of rescue out there. But sometimes rescues where the dogs have been *fostered* can be a huge help to YOU in finding a dog who may be less dominant, more tolerate of things like children and livestock and other pets.
**MY** mindset when looking for a dog is always to find the one who needs ME. That helps me walk away from a cute bundle of fur that ... well maybe I LIKE it (and sheesh, I like ALL dogs) but is it really right for us?
When I was a teenager (in my last year of high school in fact) we adopted a puppy who was MINE in every sense of the word .. but by the time I went to college (and I came home a few weekends, Holidays, summer) but even in the 2 years I was away the dog truly became my PARENTS dog.
When I graduated and got my own place ... Pip was broken hearted that I didn't stay THERE. He tried to come and live with me but really truly missed my folks SO much that I wound up leaving him there. He wanted us to be **together**.
The hard part about getting a dog in your teens is exactly that. As you mature the dog tends to bond with *everyone* so if going away to college is in your thots then you may want a dog older to begin with that will be content to look to you for training, etc.
Does that make any sense at all? I'm not trying to discourage you at all -- only to set yourself up as primary caretaker of THIS dog if you want it to bond to you?
As far as specifics -- not only would I look at the dog who looks into YOUR eyes (I like to feel a real connection ... you can guess I'm not a 'puppy person' and I like to feel that "hmm, this dog needs ME!")
I'd watch the interaction of the dog with it's surroundings -- likely you'll want a dog that's not dominant. Reserved maybe, fearful no - not if you have as 'busy' a home as it sounds like (lots of animals, maybe several humans, other pets in the house).
Now I'd take on the fearful one ... but that's likely not going to be good in your situation. If you can find a dog that has been given up because people lost their home, or couldn't afford to keep the dog ... but they HAD kids ... and heaven knows there are TONS of dogs out there now displaced by the economy. That would help you, I think