I noticed some topics about recruitment efforts and thought I could contribute as someone who has been looking for a guild these past few days. While there is an r/esoguilds subreddit, it isn’t very active. The r/elderscrollsonline sub has a weekly guild discussion worth participating in, every Friday.
For example, this comment thread from one recent Guild Fair Friday is interesting: http://www.reddit.com/r/elderscrollsonline/comments/323vvh/guild_fair_friday_advertise_your_guild_find_a/cq7ttuq
Guild Fair has posts from both guilds and players looking for guilds, and I think the biggest value is the opportunity to target specific people, which always has more impact than blanket ads.