The redditlist seems to be offline - taking part in the protest, I guess. So, looking at a recent archived version, we could always make sure we've duplicated the biggest subs, for a start. WorldNews definitely fits that bill.
Looking at what had the most subscribers in 2014 it doesn't look like things have changed much - gaming, news, funny, videos, science. News for nerds. Most all of those have been covered here, but I think it would be prudent to cover all the bases.
Also, are we going to have local communities? Jeez, "communities" is a lot of typing. Subs is 5 characters. Local "comms"? Sounds like a Hawkwind song...