The most important thing, whichever monitors you decide to go for, is room treatment.
I would highly recommend spending a little extra money on some acoustic tiles and bass traps, to set up in the room. There are plenty of methods of how to do this, but a good starting point is to trap the corners, and tile a bit of the major flat surfaces (including the roof!).
Also tile behind the speakers.
Next thing to do is to buy monitor stands, and pads for these stands, and place the monitors so that they create a perfect (as near as you can get it) triangle with your mixing position. i.e. the distance between the two monitors has to be the same as the distance between your ears and the corresponding monitors.
Then you will need a friend to help you with the next step... Sit in the mixing position and have your friend walk around the room moving a mirror around on the walls (50x50 cm mirror will do).
When you can see any of the two monitors in the mirrored reflection, you will need to place some dampening material in that spot (again, this will need to be done with the ceiling).
Now you have created the ideal listening position, and eliminated, for all intents and purposes, aaaaaaahhhhhhhhhh... I cant remember the word for it.... pre-delay? Anyway... the sound from hitting your ears twice and creating false images.
The quality of any set of monitors will be greatly improved.
Believe me, its worth the money and hassle to go through this.