I have had good luck with both brands. The biggest reason I'd go with the Kryptonite is because the $20 gets you a Sold Secure Silver guarentee, which means that model has gone through testing and is rated as resistant to hand tools for a certain amount. In reality, both locks will get you adequate protection.

As previous posters state, make sure a mini U lock can lock your bike up where you are putting it. In some locations, a mini-U doesn't have the space. Also, consider locking wheel and seat skewers (pitlocks are great, pinheads decent, even the Hublox from Delta Cycle or the Allen skewers from Nashbar or the ones with a standard key will help stop a would be thief from stealing your wheels.)

Personally, I'd go for a either a New York Lock STD, or an OnGuard Brute STD. It is more weight, but you have more locking possibilities including perhaps removing the front wheel and locking that with the rear.