Neptune is beautiful. That’s just in this solar system, though. I can’t wait till we have images of ones in others! (ok, I admit it, I’m a geek)
Uranus. No particular reason.
Jupiter, because its’ so pretty to look at in my telescope. And its moons rock.
Venus, planet of Love. Where everyone runs around naked and has sex all day.
What? What do you mean they don’t?
Well, then, Earth. But only in as far as one get’s to run around naked and have sex all day.
(And someone should speak up for Mars, which despite it’s warlike nature, is looking very pretty right now :))
Exodor- Even Pluto?!?!
Mork- Naaah! Never go to Pluto… It is a Mickey Mouse Planet!!!”
-From Mork & Mindy
In addition, we should not limit ourselves: speaking outside the Sun, we have found almost 100 more planets!
http://www.extrasolar.net/mainframes.html
So much to choose…
Mine’s the sun.
Altair-4
Betelgeuse! (well actually I’m quite fond a small planet in the vicinity)
Though Earth is moslty harmless, which ain’t so bad either 
I like Saturn…those rings are purty.
Off the top of my head:
Trantor
Remulak
Lalonde
Well World
That world in Star Trek that had the green dancer
Oh yeah, fictional planets. I’d have to say Alderaan or Vulcan.
I remember watching the Voyager 2 encounter with Saturn on TV back in the day, and ever since then it has been my favorite planet. The Cassini mission has given me a reason to live until 2005.
My favorite fictional planet is probably Bespin, because all inhabitants get a lifetime supply of Colt 45 malt liquor!
That planet orbiting the star, Emme Ya. I want to meet those fish people. Or maybe Ringworld.
Iszm. It’s a Jack Vance original.
Coruscant = urban enema (in a good way)
Saturn, no contest. If I ever have a band, I’m going to name it Cassini Division. Plus, Saturn was such a funny Plasma Sword character.
Darkover
Amber
Garth, from Brin’s Uplift War
[aside] bravo for Vetch for bringing up Vance’s classic "The Houses of Iszm. Vance had many fascinating worlds and an agile, baroque mind. Time for a major Vance revival! [/aside]
I would like to sniff the gases of Uranus.
Neptune for me. My rising planet.
Jupiter, so beautiful and violent with it’s centuries old storms. Practically a tiny solar system of it’s own and one of the more likely spots for life elsewhere in the solar sytem.
“All these worlds are yours except for Europa. Attempt no landing there.”
:>