The OnGuard Bulldog 8010 U-Lock is an excellent value in the low to mid-range priced u-locks. I have owned 2 and they lasted about 5 years each. The last one was in fact still functional after 5 years, but the mounting bracket latch attached to the bikes frame failed. With no easy fix for this, I elected to buy a new lock, which comes with a new bike frame u-lock hanger & latch.
The features I found useful in this lock:
-The long 9” length of the shackle.
-The hard to pick disc lock.
-The disc lock key inserts easily and requires no orientation - it can be inserted either way, making nighttime locking/unlocking much simpler.
-Nearly all parts of the lock have a rubberized coating, which helps to prevent scratches to your bike finish.
All and all this is an excellent & rugged lock that should last for years. It’s $30 price point makes it an attractive value.