Attic insulation question - Chicago

[Tim Coppola]

Hello everyone,

I am looking at insulating the attic of my 2-flat in Chicago and have had a few people come out and look at it. One suggested using spray foam on the underside of the attic walls (roof) and the other suggested blowing in cellulose over the floorboards of the attic. I'm just curious if there is a pro/con of either one or if this is a matter of preference for people.

Thanks in advance for you input,

Tim