I can weigh in here, I'm currently working for a prestige automotive company as a diagnostic tech too, we use picoscope as designated by the manufacturer. And, like everyone else has mentioned, they're worth the money, however from experience, you can get away with a hantek. Just make sure it's 4 channel, and you get the attentuators for use on ignition systems to protect against high voltage. As for CAN and LIN networks, a hantek is fine, the software isnt as good and can be a little buggy but for the price is fine. The biggest thing with automotive work is knowing what a good signal should look like for your specific brand/vehicle. All manufacturers use different sensors that give different readings so it's good to build up a library of good known signals on a USB for later use. Hope some of this has helped.
Ash