3) Xume quick release adapters – I use this in my current setup. It comes as 2 parts: a magnetic adapter with male threads to fit to the lens, as well as one with female threads to fit to the filter. These then will stick to each other and hold the filter in place. You can buy as many of these adapters as needed for each lens or different filter.
I bought mine direct from the manufacturer, as these were not available elsewhere back then. But I have seen these now available on eBay. They come in various sizes from 49mm (which I am using), up to 82mm.
Link to 49mm Xume filter adapter at Amazon:
I have to say the strength of the magnets is indeed very powerful. There is very little chance that the filter will be accidentally knocked off the end of the lens, unless it was with a very significant force.
I have seen videos of people holding their entire camera setup via the filter which is only attached to the lens by this magnetic filter. I too have tried it myself with my UV camera setup and it is strong enough to support it (and some more).
In use, this adapter allows me to change filters very quickly, is not bulky (fits into my little Tamrac filter pouch), and does not result in much (if any) movement of the camera relative to the subject from the filter change. Hence a big thumbs up from me.
Score 9/10 (as nothing is perfect)