I like Ubuntu.
I'm dual booting 7.10 and XP Pro, and I'm using Ubuntu more often now.
I think it's because it's a lot more popular, and finding info and how-to docs is quite easy.
Also, it's the major Linux distro, or at least the one I heard about more often.
I like GNOME and how stable everything is. I might try Kubuntu at some point, because I've heard Linux MCE is built to go on top of it, and one day I'd like a decent (free!) Media Centre.
The thing that got me to jump in a try Linux was native support for reading and writing to NTFS, so I can easily edit, and add files to my windows partitions.
I like the idea of Beryl, but without a graphics card I'm limited to no effects at all
Tbh, I was amazed at how quickly the install went, and how simple it was to re-size the partitions with very little amounts of research. The one thing that did confuse me slightly was the partitioning screen. A bit more clarity there might really help things along, as a more graphical interface, like Disk Management in XP (right click My Computer -> Manage -> Disk Management) might appeal more to the more apprehensive of us. Who knows, I might learn how to code, and get one designed. That's the great thing about Linux in general, users can learn how to create things for it!
So yeah, to answer your question, Ubuntu 7.10.