Personally, id do a local FBO, all cfi's there will be willing to fly just as much as ATP would. It would be cheaper, and likely better instruction. Especially if you can get a very experienced cfi. Hard to find at ATP.
Most local FBO's also would employ you after you get a cfi, and you can work into the charter department later on.

Effectively? What do you mean? Get the best training? Find a job asap?
Do whats best for you, go where you want to go to school. Spend the money you dont mind spending. If you want fast training, lots of multi time then sure go to ATP. But that isnt your only option for completing your training fast or getting multi time. There is no one right answer here. Thats a choice you have to make.

Its a long road ahead my friend. Enjoy the ride to where you are going.