component speakers generally have a "better" cross over.
coaxil speakers are a better design.
Ideally, all your drivers would be in the exact same spot.
Now with subs, their size requires that we move them.
Their non directionality and some other things make the trunk ideal for them.
Unless you run compression drivers on horns in a car, I would suggest coaxils in the kick panels.
Your ears are good at detecting left to right, but not up and down.
In fact, with an EQ you may be able to use psycho accoustics to raise the sound stage.
Your ears hear sound the same coming from below, except for the attenuation of a narrow midrange frequency. Relative tonal changes in this frequecy que your brain to move the location up and down. So, you can reverse it using an 31 band or better EQ.
However, I have not done this in my car or felt the need to.
Here are my pods:
http://www.sounddomain.com/member_pages/view_page.pl?page_id=134802&page=3
Location will almost always have a greater tonal effect than the difference between brands of speakers.