I have had good results with the Pollak brand battery disconnect switches. They come in both keyed and unkeyed versions, and seem to be well-made. Note that the keys are all the same and are simple warded keys, similar to the Cat ones. When my house was being built and the guys on site didn't have the key to the New Holland skid-steer with them, I found that its ignition switch used the same Pollak key, so I got it started for them without their needing to call the boss.
![Wink ;) ;)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
The Pollak switches show up on eBay, among other places. They're neither the cheapest switches nor the most expensive, but they seem to be the best-quality ones I've been able to reliably find so far.
I've had experience with both the green-knob and knife-switch disconnects that mount on the battery terminal. I consider them to be junk.
A while back, I picked up a Harbor Freight no. 66789 "Heavy Duty Battery Cutoff Switch" at the local HF store. I haven't used it yet, but it appears to be better-made than the usual electrical stuff at HF... maybe even good enough to use! It claims to have been made in India. Have any of y'all used this switch in diesel/MV applications? If so, how has it been holding up? I've had it sitting on my desk for a while, and so far it hasn't fallen apart from idly flipping the knob somewhat roughly.
I've seen and used HF's knock-offs of the Hella switches before. They don't show up on their web page now, so maybe they no longer carry them. I've used one for a light-duty application, but I wouldn't trust one in one of my MVs, or anything I care very much about. They seemed somewhat cheesy to me.