Hi All,
I like Redhat Linux ditros AS, ES, Fedora..., may be because I'm familiar with it, and looks to me quite stable, packages management is very good.
Added to that, various tools especially for entreprise applications.

I really like DSL (please excuse the profanity in the name of the distro ) because of its really small size. When compressed it weighs in at less than 50 MB and has a fully functional desktop (fluxbox), web browser (Dillo and Firefox), office suite (Beaver, FLWriter, etc.) and many other pre-installed programs. It is small enough to boot from a business card size CD and can perform a USB boot (with floppy support if needed). It also has really low memory consumpiton compared to other operating systems; for quite some time I dual booted MS-DOS (with Windows 3.1) and DSL on an old Compaq laptop I had sitting around and now it's not collecting dust anymore! Both operating systems coexisted quite nicely together since MS-DOS can be booted from a floppy and I can create a small partition just for Windows and a larger one for DSL, plus an additional partition for all my programs (I thought I would eventually install Wine so that I could use DSL in place of Win 3.1). DSL helped put new life in otherwise almost worthless hardware.

I voted for CentOS, it same RHEL. Using easy and powerful

Currently using Debian Etch. Nice and stable.

If I need anything more up to date (not that Etch is ancient) then I load it into VMWare.

Although I started out with Berkley UNIX in the 70's, I have used several distro's of *NIX since then. At present, I use a rehash of Ubuntu 8.04 known as Ultimate Edition 1.8. I like the distro for the intergration of compiz/beryl and the eye-candy helps me sell folks on Linux. Personally,anything I can do to forward the cause of open source is a good thing. Many of my customers (I run a small computer shop) have never heard of Linux or have no idea that it has advanced so much. The distro I run helps me convert people to open source. They see it and like it. Ubuntu has my vote.