The best sounding one of the 3 is the Monitor Audio, and at its current selling price its probably the best value one as well, we have it discounted by 60%. The other two cant keep up in terms of sound quality, but theyre both more compact and are actually cheaper. I would choose the Monitor Audio based on that unless its too big for you to fit it in.
I would put the Q acoustics as and Canton ones as fairly well matched on sound quality so I would maybe pick based on how they look as much as how they perform. The Q Acoustics is the most compact, you may find the Canton sound base too deep in some scenarios. The Canton is the more powerful of the two so will give a bit more output, which is to be expected given its a larger unit as well.