I've tried the following:
Ubuntu 5.04 Hoary (my first Linux distro): Coming from Redmondland, I was impressed. Not because Ubuntu was better than XP, but because I had no idea Linux could be that easy to install and use.
Mandrakelinux 10.1: Looked better than the Brown Hedgehog, but I couldn't get my cable modem connected through USB. After hours of scratching my head, I went out for a cigarette. When I came back, my display looked like a code bar. I figured it was some kind of screensaver, but it turned out that my system was frozen, so I gave up on Mandrake.
SUSE 9.3: I couldn't wait for SUSE 10.0, so I tried a netinstall of SUSE 9.3. I was glad my USB cable modem worked, but at my connection speed it would have taken me at least one day to download the system. So I wiped my tears and aborted the install.
SUSE 10.0: No USB connection, unstable and slugish (on my hardware).
Ubuntu 5.10: Getting better, but not quite there yet.
Mandriva 2006: USB connectivity at last!!! ...and rpm hell...
Debian Sarge: Tried a net install. No USB connectivity, no install. Shame! But hey, I tried...
PCLinuxOS .92: Polished, stable, impressive... but not quite there yet. Not enough packages. But it was the most newbie-friendly I've tried and everything worked out of the box.
Ubuntu Dapper: I can see the new looks (and not necessarily like it), I can see the bugs (and I don't complain, since it's an alpha), but I don't see no stinkin' speed improvements! Not on my hardware (i.e. Athlon XP 2200+, 1,8 GHz, 512 DDRAM, ATI RADEON 7000 VE 64 MB RAM).
I should add to the list countless Ubuntu "colonies", "flights", betas and RCs.
I'm thinking of giving Fedora Core 5 a try, but I have mixed feelings about this distro. Maybe that's a good sign. Wish me luck!
Oh, and I'm also looking forward to testing another beta. It's a little-known distro called Windows Vista, put toghether by some script kiddy called BillyG. I'll let you know how it went.