If not 24-105mm L series, then what?

[BecdS]

I'm ready to make the giant leap out of kit lenses (except for the 50mm prime). I thought I had absolutely made up my mind on the 24-105mm L lens, until I read through a thread here. I was shocked by the number of people experiencing the exact same problem, one that Canon swears they know nothing about!! If I'm going to "invest" this much money, I shudder to think of paying the $300+ repair bill through no fault of my own.

The reason I settled on this lens as my first foray out of the kit lens wilderness is because of it's all-round usability. I've chat with a few auspho-folk and this is the lens (at least this length) that's been most often suggested. I'm a beginner, but I would like to start building a useable kit. At present I'm practicing portraits and shooting things reasonably close, using the 50mm.

I currently have: Canon 350D, 50mm 1.8, Canon EFS 18-55mm, Canon EF 75-300mm.

Where to from here?