Which Dog Breed Will Suit Me/my Lifestyle??

ok so im at home pretty much all week * i work only on wednesday,friday and saturday) from 6am to 11am
i want a companion dog that will be very energetic,playfull and not too big
i have a one family/flat house with large backyard
i was a dog breeded so i know pretty much everythign about care,training and owning a dog
i bred giant dogs ( newfies and giant schnauzers)
i did my research yesterday and im thinking about one of those breeds :
mini aussie( australian shepherd)
sheltie
greyhound
or american eskimo dog
i no nothign about those dogs besides what i have read
i need more information before making any decision
what i need to know is:
exercise requirements
grooming ( i know that long hair dogs need lots of brushing from past experience with nefoundlands)
and im willing ot take the dog out like 3 tiems a day for 1 hour long walks
will that be enough???