My most secure setup was a Kryptonite evolution mini with a cable!
The U-Lock kept my frame safe, and the cable deterred wheel thieves.
I used this setup over night in various moderate crime areas and still had my bike. lol.

I've sinced switched to an Abus Bordo... ITs a folding lock that has a very small size and is extremely convienent. It folds out into a giant loop that can wrap around the thickest of telephone poles no problem. Its rated a 8, which is the same level as abus's lowest end U-Lock... So I'm sure its good enough!