What kind of guild environment do you like?
From this I am referring to whether you like a quiet guild or a chatty guild - is there a happy medium? I have noticed that the guild I have joined never says anything in guild chat and you really have to push them to chat?
When the Elephant and I started the guild, we'd had quite a bit of experience of what we didn't want in a guild, so we aimed to fulfill all of the goals of what we wanted in a guild with the help of some real life friends, and some good friends we've made in WoW.
Now, I don't want this to seem like a plug to join our guild because of X, Y, or Z, but I just want to gush about why I love my guild and guildies, and why I consider the Elm my home and the guild my family. So please, only take it as it's given. :)
While the guild has its quiet moments depending how many members are online and what they are participating in, generally the guild chat is going. Sometimes about WoW topics, and other times about other games, and sometimes poking a little bit of fun at each other. It's the chatty environment I've always wanted, and that I had had in other guilds I have fond memories of.
Run Old Content
I've always enjoyed running older content. Mainly for posterity, and because I love the environments, especially in the BC era. My perfect guild runs old content on a regular basis. I like running old content for items and gear, to spend time joking around and having fun with my guildies and to grab some achievements.
Speaking of achievements and old content, I love guilds that do this together. Whether it be runs for a Bloodbathed Frostbrood Vanquisher or an Ironbound Proto-Drake, or even just to kill the Whale Shark, I love getting achievements with guildies. I love running "Fun Nights" with guildies that also want specific achievements. Now, while the general population of WoWers doesn't lust after having Over Ninethousand achievement points, a lot of people do want specific achievements. And I love helping them get those achievements. Including the PvP achievements they're interested in.
Though I haven't run many lately, I love battlegrounds. And I love running battlegrounds with my fellow guildmates. I just love the atmosphere of smashing Gnomes together in all of the neat environments Blizzard has implemented for Player on Player combat. It's a favorite pasttime of mine, much like raiding.
Current Tier Raiding
Now don't get me wrong, raiding older content is really fun, but raiding the new content is even more fun. My server is kind of dead (at least Horde side) now that some of the top raiding guilds have transferred elsewhere. My guild is currently clumped with a lot of other guild sitting at 6/7 in Firelands. Thanks to some very talented individuals we've made it really far this expansion. While we'll never be world-first or even server-first, we're proud of the progress we've made. Both raiding groups have come a long way from the start of the Cataclysm expansion, and we plan on moving at our own pace.
All-in-all, I think the perfect guild for me is the one I'm already a part of. :)