Gutsy or earlier
7.04 - Feisty Fawn - was the first Ubuntu release I installed, liked, and kept. I would call it the best, but it's probably not a very objective judgement. I have fond memories of it, and whatever didn't work has been forgotten.
My first impression on 7.04 was that it was ugly as hell, and I got away from brown as quickly as possible. By 8.04, Hardy Heron, I'd changed my mind about the color scheme, and actually liked the default look. It was an acquired taste, I guess. I don't particularly like the new look.
Feelings aside, I guess the most stable and reliable Unbuntu release I've used was 10.04, Lucid Lynx. Everything just worked somehow. That was nice. Boring, but nice. I haven't liked anything since Unity/Gnome-shell.
Don't eff with The Cult...
Everything worked hunky dory and it had a kewl name !!
For me either Breezy Badger or Dapper drake. I'll say Breezy because that was my first, it got me hooked and i liked the boot screen. Now I'm torn between Windows 7 and Ubuntu.
i liked jaunty jackalope
used jaunty, lucid,precise
only started with precise in the past couple days, and had do do a lot of system mods to get my self happy with it
seems to require more and more mods with every release
12.04! So far I love Precise and the Unity Desktop!
Maverick to Natty to Oneiric were all rock solid for me; Regardless what DE i chose, or the amount of DE sessions i ultimately added.
12.04 though, has major issues on the same hardware i have used since 10.04...
Everyone who is saying Precise is the best release, must have spot on hardware or something. Though i have heard that Ati drivers/cards have been a cause of this, so i am looking into a Nvidia.
I'd have to say Feisty Fawn was the best in terms of how much it improved on previous releases. It was always a hassle to manually install the w32codecs to get videos playing perfectly.
That and installing video drivers to get beryl or compiz running was also a pain. I remember breaking X so many times in doing so, lol. And I hated turning to third party programs like Automatix and Easy Ubuntu to get basic stuff like this done, so when Feisty Fawn came out with a built-in codec finder, the restricted drivers manager, and an option to enable compiz, I was totally impressed.
Lucid worked very well with few hassles.
Precise has basic issues like the speaker volume being ridiculously loud after boot up. Volume control has to be adjusted to reset the levels.
Printing to an older HP most often wastes 4 pages printing header info before the page intended actually prints. This is a bug and has not been fixed yet.
I'd have to say Lucid but I've only tried 3 really, Hardy, Lucid, and now Precise. Oh wait, I did work my way up through Intrepid, Jaunty, and Karmic in an upgrade from Hardy to Lucid. I really wanted to like Precise, but it's too different and hasn't proven to be very configurable. Fortunately alternative DEs can be installed to make it better.