You're wise to tackle this home improvement project. Attics offer the greatest potential for home energy savings, and also happen to be the easiest area to improve. Whichever insulation material you choose for this space, make sure to maintain proper attic ventilation. It'll protect insulation from the dampness of wintertime condensation, which can cut insulating power by one third and introduce a host of structure-threatening moisture problems.Now, in terms of your specific project, you have the right idea: You have to resist the urge to overstuff those 2x10 bays with insulation. Insulation works on the principle of trapped air, so if a space is too compressed or overstuffed, the insulation benefits are reduced or even eliminated.
You asked about batts versus blown-in insulation, but I recommend a third option: spray foam insulation. I insulated my own (older) home with spray-foam insulation recently, and it drastically decreased my monthly utility costs. Specifically, I used Icynene Spray Foam Insulation, which you can install in one step. Icynene is formed through mixture of two components—ISO and resin—which react and expand to create tiny bubbles in the plastic matrix that fill and insulate the space. Good luck, and let us know how it goes!