MW2 VS MW3 Which one worth buying?

Good morning/night, I am a new player in the cod franchise, And i really wanna know if i should get mw2 or mw3, Since there is a huge debate between them, MW3 is a bit expensive so i might settle for MW2, But regardless i wanna know your thoughts :)

Note: Not important but i am getting the Disk version of whatever game i pick, Since it is a bit cheaper.