Electric Fans 12 vs 14

[hotwhls]

This winter I am going to install a electic fan as a pusher. (No room for puller) I am looking at getting a 12in 2300 cfm or a 14in 1850 cfm fan. The Radiator is only 16.5 tall so I can't go any bigger than that. My question should I go bigger with less cfm or smaller with more cfm. No I will not shroud the fan either. Whats your oppinion is the bigger fan have more cooling since is will take up more area on the radiator or will the smaller the fan with more cfm cool better.