Collies and Springers need LOTs of exercise, too much for normal people to fulfil. Been there.
We've a black lab now,and has been the best dog we've ever had. He's not greedy, walks well on and off the lead and is as soft as a bun. Lovely temperament. Loves swimming and diving for stones from the riverbed. He's got a bit of a thing about collecting sticks and plastic bottles when he's out. Downsides are thet he drops a bit of hair when he's moulting, and can't stop himself from sitting in muddy puddlees or rumping in the river when smells water.