Teeshot, just ignore the posts that have nothing to do with your original topic, or move the discussion over to Whatsbestforum. That is a generally more serious, less contentious forum.
I happen to think that your original question is pretty interesting. The speakers do sound different and they are quite different in size. Perhaps the size of the room and the amount of power that your amps have could be the determining factors. The Q3 is an easier load to drive and might be more appropriate in a slightly smaller room. The M5 is less efficient, has lower extension and will pressurize a larger room more easily. The M5 and Q3 are also quite different aesthetically.
Then there are resale and repair/support issues that you might consider also.
I happen to think that your original question is pretty interesting. The speakers do sound different and they are quite different in size. Perhaps the size of the room and the amount of power that your amps have could be the determining factors. The Q3 is an easier load to drive and might be more appropriate in a slightly smaller room. The M5 is less efficient, has lower extension and will pressurize a larger room more easily. The M5 and Q3 are also quite different aesthetically.
Then there are resale and repair/support issues that you might consider also.