I definately, as John stated, like fiberglass between the rafters better than blown in.
But, they do have alot to do with your budget at the time. Blown in is cheap and easy to do and can be done rather quickly. you do need two people, one to hold the nozzle end of the system and another to chop up and pour in the baled celose. One bale is about $3 and the machine in free if you buy 10 bales. Quite a deal.
Now, the down side, you do have to consider the insulation in the attic now, It has surely compressed, but the weight is still there. You need to think about total square foot weight of all that insulation in the attic or it could all come down on your lap while watching Survivor.
So do consider this. Then consider that blown in will compress rather quickly or settle might be a better word. Nice and fluffy insulation is more effective than compressed hard insulation.
Between the rafter insulation takes longer, cost more money, and will last much longer in the long run.
Remember, when you attempt this project, take up a 3/4 inch sheet of ply wood as wide as you can for you to lay on and to straddle the joists. Most everyone once in thier livetimes will fall through the rafters and have a leg or torso come through the ceiling. Be careful and use the sled to move around on.