Solid Hardwood, Engineered and Laminate Flooring - Adding subfloor thickness

I need to raise the subfloor in part of the house by 1/2" to match the flooring in the kitchen. The existing subfloor is 1-1/4" plywood.

What material should I use to add the 1/2"? I've thought of OSB, MDF, and Plywood. I'm kinda leaning towards MDF since I don't need the structural strength, just filler. Besides, it's cheaper, smooth and hard.

Is there a preferred material to use? Also, what is the best method to attach the new material? Glue, nails, screws?

Thanks,
Kevin

Use a exterior grade 1/2" plywood. Don't use MDF. MDF doesn't like to be screwed down and is a sponge for water.

Glue and screw the plywood down.

Plywood is the best. OSB, is acceptable. MFD would be a wast of money, under hardwood, and I don't mean the cost of just the MFD, either. You will be redoing the wood flooring, unless it is a floater.

Thanks guys, I'll go with the plywood. I only need 8 sheets, so that's not too bad. I guess I forgot to mention in my initial post that I am installing a floating laminate. The kitchen, and the bathrooms too, has 1/2-inch particle board under the linoleum on top of the plywood subfloor.