depends entirely on your purposes.
Single hanging cages means NO contact between rabbits. So they are helpful for isolation purposes. The space difference also means you can hang things between cages (for instance if you have a sneezer that you are monitoring, or a buck that sprays). They are significantly easier to clean and move about. Long sets take a careful hand and strong back to move around well.
Long rows mean that lonely bunny types can snuggle up next to the rabbit next door (unless they hate each other, and then it means potential for bites through the wire). long rows save huge on wire costs and save tons of space. Long rows make it easier to feed them as well, and are often easier to hang.
I think should I have opportunity to have a barn with cages I can set up at what I think is a good height I would like cages that are all separate in the long run, except for grower cages. Grower cages I'd like to have in rows of them. Like two 2 x 36 in a set, then three 2 x 30's and then four 2 x 24's. Starting with bigger cages for whole litters, and gradually move them down into smaller cages as they get bigger and I wean out the ones I want to keep. Since they are only in them for a shorter period of time, ease of clean out isn't as big a concern for me.
The girls I'd like to keep in individual cages with sets of brood cages that are larger then normal. Just so they have space to move about and prevent clumsiness. I'd redesign them with under wire nest boxes. Or boxes that hang off the back or something. Not these boxes that I have to set into the cages.
But then I also want to be able to keep my bucks in large runs (on concrete) with litter boxes.
Get them out of the wire cages and let them just be bucky and funny in bigger areas.
