What you haven't told us is where/who you plan on buying this from and what the full component listing is.
Having said that Sager has a better cooling system than ASUS but ASUS tends to be a little cheaper on pricing. Assuming we are talking about stock configs the Sager is going to be better performance via components alone. Not by huge amounts but enough to say it is better. I'd go with the Sager if you can afford it. And buy it from someone like XoticPC, PCTorque, GenTech, etc., They'll have the better customer service than the parent manufacturers whichever you choose.
Just my 2 coppers anyway.
-SG03 Case, Corsair H50, 1 - 120mm Scythe S-Flex SFF21F Case Fan, Corsair HX520w, Intel i5 750, GA P55M-UD2, 4GB GSkill RAM, Gigabyte GTX460, Lite-On LH20A1H, WD6401AALS 640GB HDD, X-Fi XtremeGamer, XP Pro SP2, Logitech G5,Saitek Eclipse II, 22" 1680x1050 LCD
-Lian-Li V354, 4-Noctua NF-P12 120mm fans, ASUS P8P67-M Pro, 8GB GSkill RAM, Intel i5 2500K, Corsair H50, WD Black 1TB HDD, Optiarch Slim ODD, ATI 6950, Corsair HX850w, W7 Pro 64, Logitech G5, Saitek Eclipse II, I-INC 28" 1900x1200 LCD