I've heard the Logitechs and the HK and I would say you should get the Logitech, I just found the sound coming from the Logi speakers to be a bit fuller and didn't rely too much on the subwoofer to deliver the lows. Also the HK looks like a jellyfish...
But I have also heard very good things about the Klipsch speakers and the thing about those is that it has a tweeter built into it so it will give you a fuller range of sounds, but then again its about 2x the Logitech ones.
But I would definitely go for the Klipsch if I were you. Also if you don't mind spending a bit more you could get a pair of bookshelf speakers, that way you wouldn't even need a subwoofer because they usually deliver incredible lows w/o a sub.