Another vote for Helix. Running silky smooth for nearly a week now. Not sure what you have in mind by "best looking".... Helix doesn't have a ton to it, other than multiple homescreens, shortcut options at the bottom and auto-rotation for the homescreen. These are the only features I currently want and I like the simplicity (less moving parts = less chance for problems) so it works for me. But I believe some others (GDE, Panda, SweeterHome) offer more customization/"look" options.
Been going back and forth between GDE and Helix for the last few days. I do like the cube effect for screen transitions in GDE but have been trying Helix to see if the occasional lags in GDE were eliminated with Helix.
Haven't found it to be so. I suspect it has more to do with memory management in the Droid when the homescreen is first loaded than with the homescreens themselves. (I'm using seven screens in both GDE and Helix and I suspect that is the culprit.)
With fewer home screens there might be a difference I'm not seeing.
Otherwise, for me at least, it comes down to the full rotation of GDE (no back and forth among screens) versus the double-tap to show all seven screens in Helix. Haven't decided which I like better.
I use helix mostly now, mainly due to the double tap cards that pop up and the place for shortcuts next to the launcher. I like panda a lot though I found it to be very customizable and I was able to make my phone look great using it, i like how you can customize everything using it for those of you who don't have bettercut or the time to use bettercut I think panda is a great option.
I love the application docks and being able to skin the icons in them (using Bettercut) to match my theme. I use the Glasklart icon pack btw.
As far as "the best looking home replacement" I suppose the award would go to sweeter Home 2 in that it allows you to create whatever your heart desires, provided you have the time and patience to design your screens.
Have been using dxTop for months and really like it.
The recently added screen transition effects are really cool.
Also, I really like the ability to add widgets to the 'dock' (swipe app drawer and add 5 shortcuts/widgets/folders) and the ability to categorize apps.
Helix 1, it's simply the most stable thing out there. It's even more stable than some of my applications, having never forced closed or even had a hiccup. It's flawless.