I don't think you can go wrong with a Kryptonite D-lock, I've used different ones over the years and found them to be excellent. The mounting bracket is decent as well, but I don't use it as I always have a bag with me.
You have to weigh up how much your bike is worth when considering buying a lock, i.e. no matter the cost of the lock, if your bike is nicked, you're still down a bike.