I think it tends to fluctuate as different storylines in different soaps catch the public imagination. Over recent weeks Eastenders has been dominant as the excitement over the culmination of the 'who killed Den' storyline escalated, further fueled by the return of the Mitchells. At other times Coronation Street, Brookside and (perhaps less frequently) Emmerdale have all had their moments in the spotlight. The 'Free the Weatherfield One' furore was particularly high-profile.
I suppose as well you're always more aware of the soaps that you and your social peers follow as well. I rarely find myself embroiled in a discussion about Eastenders, but frequently debate the goings-on in Coronation Street or - most often - Emmerdale (in fact, I've been known to spend my Saturday mornings happily ensconced on the sofa watching the ITV2 omnibus, keeping up a text-discussion with my similarly occupied mates as the story unfolds...... Deeply, deeply sad, I know.)