Surround speakers: Better ones at rear or side?

I have two pairs of monitors I'm going to use in a home theater setup. One pair is far better sounding than the other. Which pair should be the rear surrounds and which the side surrounds?
The rears will be placed 8 ft behind the seat and near the ceiling. The sides will be just behind the seat, on the side wall.
My suggestion is to place the better speakers closer to your ears (the side speakers), and the lesser-quality ones farther from your ears (rear wall). If you can aim the rear speakers to bounce off the ceiling, it will diffuse the sound more, and make the quality difference between the speakers less detectable.
Better speakers up front ,rears don't  have to be as good.The mains will be needed to be well the main.The rears more sound effects .
Obviously, your front stage is the most important like limomangus said, but I'm assuming you're only asking about surrounds.

Side surrounds speakers should be better than rear surrounds.  Side surrounds still has some direct sounds generated (in movie soundtracks).  The rear surrounds are more for ambience and reflective sound.