From the options given, the SKS.
If I had my choice, an M14. Why? A long time ago me and the M14 bonded. Pretty decent long range accuracy, with select fire a feller can set up a pretty good killing field.
Mikey, the M60 is a good choice, but it's too heavy for me to be totin around anymore. My legs just ain't what they used to be in the '60's. :? Now, for a fixed position...........