Budget ? Where is it being left ?
I use a decent d-lock at work and an ABUS Bordo for the front wheel. I am in a secure shelter. If it was left in a less secure place, I'd be getting my New York FAGH Mini D lock out instead of the reasonable d-lock. I suspect the New York lock will be coming back out soon as our staff shelter is being opened to students.
Not that I don't trust students, but more users means 'tailgating' into shelters. We've had this already, someone tailgated into a staff shelter with a bike. Waited, propped open door, put own bike outside, back in, cut lock off another bike, and off they went with both bikes - all on CCTV. Owner did have a crappy combination cable lock on a £1k bike !