I narrowed it down to the Altec Lansing FX6021 or the Logitech Z-2300.
I own the former, and gave the later a strong consideration before making my decision. While it's true I've only been able to hear the Z-2300's in stores (where even great speakers can sound bad), compared to the FX6021s in the same store, in my opinion the FX6021's won hands down. Once I got them setup at home I was very impressed and am extremely happy with my decision.
I
also own the Z-5500's, connected to my humble home theater setup. I think they sound great and the subwoofer rattles the walls and has very rich sound. But, it's also my option that they really only sound their best with DVD's (also including digital cable shows with 5.1 audio) and video games. Music sounds OK, but maybe I just prefer a slightly different sound when listening to music... how can I put it... I didn't think there was enough "definition" in the music, it just wasn't very "clear" sounding when listening to CD, and didn't pack much of a punch with the subwoofer as compared to DVD audio (music as mastered for a DVD movie soundtrack tends to sound really good).
So I kind of have the same complaints about the Z-2300's, only more so. I thought the overall sound was kind of weak and muddy. The subwoofer probably produces a fair amount of boom when adjusted properly, but I like my mids and highs to sound good first, which the FX6021's do
extremely well. I wouldn't put down the subwoofer either — I only keep it at about 50% and it's quite enough for me (and my neighbors probably

).
What it comes down to is this: If you got the Z-2300's, they'd probably sound pretty good when playing games or watching videos. But for music, no, I would absolutely have to
pick the FX6021s. Their "in concert" technology really does make a difference... and the "wall of sound" the tall satellites produce is nice too! Also, I was pretty blown away by the sound when playing Half Life 2 on my Mac Pro.
I stand by my opinion that you just
can't get great sound out of tiny satellites. I've never seen it happen. Bigger speakers always sound better.