Everything else being equal, a 6X9 component set can sound better than round.
The problem with 6X9 components is that there are not as many choices.
And if someone tries to claim that 6X9's have more distortion because of the cone shape, don't believe it, that's an old wives' tale... they don't know what they are talking about.
If I have time later, I'll look around and see what is available on the market this year... but I can tell you this.. the new Image Dynamics XS series will be one of the best for the money, and one of the best period. They are due to come out any week now.