I need 4 sets of brushless motor, which one should i go for.?

1. Multistar 2212 - 920KV Multi-Rotor Motor Set w/CW and CCW Threaded Shafts
2. Avionic C2830 KV850 QUAD brushless motor
3. Multistar 2213

Or any other.?
Weight of the quad estimated: 2Kg.

For a 2KG AUW, none of the above will be that efficient.
If you can Limit the AUW to 1.5 - 1.8(max.) You can go with 2212 motors and in a very low budget

Edit : Turnigy Multistar motors are very efficient- they give more flight time - If you have the budget go for it

If its 1940 grams go for sunnysky 2212 will 11" props
Best motors for a quad

http://rcmumbai.com/index.php/product/sunnysky-x2212-kv980-brushless-motor/

If you do go for these motors I would suggest you buy these to replace the stock prop nuts: http://www.ebay.in/itm/M5-Hex-locknuts-High-Quality-5-Pieces-/191023074309?pt=IN_Toys_Games_School_Stuff&hash=item2c79dccc05 I had problems with the nuts loosening or falling off mid flight    but these solved the problem. One advantage of using the Multistar 2212 motors is that they come with CW and CCW threaded shafts that will prevent this loosening.

@chintal, SS X2212 i no doubt good (i must say excellent motor) but 11" props adds a bit of heat to it. And its not suggested to use 11" with this motor for every flight cos it decreases the life of the motor.

IMO:
For 2212 980KV
with 11.1V 1045 is best suitable
and with 14.8 8045/9045 is best
saying that i dont disagree with what Chintal said but continuously using 11" would degrade the life.

If you want to use 11inch props then 2216 SunnySky should be your choice..