This month topic is brought to us by L'Dene Bean of Nitpickin's who asks: Why, and how did you pick your corporation? Is your loyalty solid or just until a better placed organization "recruits" you. The shorter version: Who holds your Unshakable Fealty and why?
So this is an interesting question, since I run multiple accounts and multiple characters (yeah, how do I manage that, exactly...) Without giving away details, my personal (not character-specific) loyalty is to the first corp I joined. They are a good group of guys (although many are currently away from EVE) that I still chat with out of game, even though they may not be playing right now. The only reason my main left that corp was to maintain my 0.0 PvP lifestyle - the corp was too small for the alliance we were in (as far as active PvP toons) so we did a pseduo-merge with another corp that was in alliance, basically mothballing the original corporation until better times (a.k.a. more game time for the veterans to be able to effectively recruit and train new members). If that corp became an active PvP force again I would (with due consideration and notice to my current corp) head back at my earliest convenience - to fly with guys I like personally.
This is not to reduce the value of my current corp. I have flown with this group in multiple alliances, other members from my old corp are also here, and the group is just as solid, reliable, and entertaining as my old corp (which makes sense, since we were in multiple alliances together and we all got along already). The trend here? It isn't the corp - it's the pilots. That should make sense to anyone who has played a multiplayer game - the appeal is the players you fly with - where they go, you likely will go as well if they are a group you are close to. I even experienced this recently with an RL friend who played EVE with a different group originally. His core group of players had a corp collapse, they all went different ways, and he joined up with my corp for a while. Now that his old group is re-forming, he has left (best of luck!) to fly with his in-game friends - and I understand and respect that completely.
If you are playing EVE, and you don't play with (not just against) others, you are missing the biggest part of the game, and the main attraction to the game - the social aspect.