I've stuck with wearers as much as anything because keeping one sow I can get my head round but two gives a lot of extra pig to feed or too many piglets. There is a trend round here even at livery yards for horses to be individually turned out with electric wire between them they always seem to stand in the plot hardly moving and look miserable. My horse runs with 4 others in a permanent herd and it may be anthropomorphic but seems a lot happy for it. Having said that 2 horses always means over dependency/ separation anxiety 3 is a lot easier to keep as a rule than 2. And of course 4 means you can take 2 out and still have a pair.
So I've stuck with wearers as it won't be 1 or 2 or 3 but 4 or more.
Now cats...that is a species that loves to be alone. If only pigs were cats. But with less fur of course.