Socom 4 US Navy Seals or Dungeon Siege 3?

Hey! i'm a HUGE fan of both game series and i'm wondering which one should i get? i'm not thinking of buying both but if i can find em cheap then i guess i will, i'm an air ventilation cleaner..... :) How different are they to previous titles of the series? (eg. Socom 1,2,3 & DS 1,2). Can you give your honest opinion about the game if you've played it.