Almax are very good (at least in their own cropping test), but you have to question how many thieves will go round with 5 foot bolt croppers. If they come with power tools, they'll all go quickly (but noisily).
The bigger factor IMO is making sure the chain is just long enough to get round everything and the anchor, leaving nothing resting on the floor. They're much harder to cut if you have to do it in mid-air. Wall anchors can be better than ground ones in that respect.
As said, if it's too much to defeat the lock there's plenty of other expensive stuff to either unbolt easily or cut through the frame to take in one piece – my old Orange C16 was stripped when their attempts to get through the Squire D-lock failed (and bent the frame in the process).
Remember too that if they want it that badly and it's worth their while, you might get woken up by someone demanding the keys instead.