Social benefit

Tamarind of Righteous Orbs nailed my attitude towards Cataclysm heroics by saying:

The thing is, spending time with guildies can be, and should be, seen as an end in itself. Presumably we’re hanging around in a guild because we like the people there. Playing together is for funz. Whereas running dungeons with pugs is merely a means to an end – we’re doing it for in-game rewards, there is no additional social benefit.

In Cataclysm I only tried very few PuGs, which all sucked horribly (up to and including joining a group which was in combat, and already wiping, so apparently they had pulled in spite of their previous healer having left.). So now I rather do guild runs, even if those go to normal dungeons where I can gain nothing but a bit of reputation. Because the longer I play, the less I care about how shiny my gear is. I'd rather have the "social benefit" of having fun in a guild group, than a gear upgrade from a pickup group.