Like pus said, It's personal preference. Knowing me, I'd definetly go with the SIG as I love them, and everyone who has ever owned one before usually comments on it as being a great little gun. The metal body might be a bitch to find though... as far as I know, only Hurricane makes one.
Or, if you can wait and save up some cash, ICS recently came out with a SIG line that includes the 552.. which probably comes full metal.
Guardians of Asgaard - KF25 -
Primaries: LCT AS VAL, Real Sword Type 56-2, VFC M4 CQB Mk2
Secondary: Latino heat, TM Glock 17