I have a great love for blue heelers: 
But ... and this is a significant but: they are extremely human-focused. If you don't think you can handle getting that 'WHAT NOW MAMA' look for 16 of every 24 hours in the day, or if the idea of trying to keep a very, very smart breed entertained through their waking hours does not sound practical or enjoyable ... maybe something else. Because they will make their own entertainment if you don't provide any, and the way they do so may not be entirely to your liking.
Greyhounds are also a wonderful low-maintenance dog. I know everyone thinks of them as sprinting all over creation, but the truth is they're active for about thirty minutes every day and sleep on the couch for the other 23:30.