In my opinion it depends on
In my opinion it depends on how much your bike is worth, Ive always thought about 5%-10% of your bikes value is fair to spend on a lock. Cant go wrong woth kryptonite, try and get a d-lock with as high-a-rating (gold is top dog) as possible. Some of these come with a form of insurance for your bike too so if your bike gets nicked while locked up then kryptonite may refund the cost of the bike. Granted they dont look cool and are heavy but if it stops your bike getting stolen…