I think this is sometimes a very subjective topic. For example, I LOVE my Z5500 system that I've had for years. It's loud and bassy and I use it for everything because my PC is for gaming, movies and music (I jam along to tracks on my guitar, so I needed a loud enough system to compete with a Marshall 100w amp
)
So for me, my Logitech system has never failed me after many years of use and I've never felt a need to even consider an upgrade. I only came to this thread to see what others are saying about newer systems than mine.