Sako or Cooper are excellent choices but I can only speak based on reputation since I have never owned either. I love the look of the Coopers and would personally choose it first and as you said, guaranteed accuracy!!
The Varminter is our most popular style, available in our Model 21, 22, and 38. All Varminters are single shot bolt action rifles that present superior accuracy in a variety of standard and wild-cat cartridges guaranteed to shoot 1/2" 3-shot groups at 100 yards (test target proving rifle accuracy included with every Varminter). Also available left handed.
Technical Specifications
Model 21
Caliber 223 Remington AI (single shot)
Barrel 1.0 x .775 x 24'' stainless steel
Twist Rate 1 in 14
Action
3-front locking lug bolt action SINGLE SHOT
Magazine None
Extraction Sako style machined from solid bar stock
Receiver Length and Width 1.155'' X 7.75''
Ejection Plunger style ejector machined from solid bar
Trigger Fully adjustable Single stage
Trigger Guard Machined aluminum
Grip Cap None
Metal Finish Matte
Stock AA Claro
Cheek Piece None
Checkering Pattern 2-panel on grip
Butt Pad Pachmayr rubber
Sling Swivels On request
Length of Pull 13.75''
Avg. Weight 7.25 lbs.
MSR $1495