The Queen's gambit, with no doubt.
King's Gambit Vs. Queen's Gambit. Which one is better?

The Gambit of Morphy, Anderssen, Steinitz, Bronstein, Spassky, Morozevich, and Shirov, of course--the King's Gambit!
What about Speilmann?

The KG gives away a pawn for development and initiative (and possibly to help control the center) with no thought of winning back the pawn (in fact in some variations, white also gambits a piece, even two, in addition) and is a true gambit. The QG offers a pawn with the knowledge that if the pawn is accepted, it will be reclaimed, so it's a pseudo-gambit.

You've gotta' be kidding me!
The Gambit of Morphy, Anderssen, Steinitz, Bronstein, Spassky, Morozevich, and Shirov, of course--the King's Gambit!
There is no opening with a richer history of providing an avenue for good, classical, attacking chess than the King's Gambit!
1. The Queen's Gambit is not even a gambit!
2. Compared to the King's Gambit, the Queen's Gambit is boring!
3. Black decides where the game is headed in the Queen's Gambit, whereas White decides where the game is headed in the King's Gambit!
Pretty clear-cut choice, don't you think?
The Gambit King
"You've gotta be kidding me!"
Nope, from my experience, those who prefer the QG are pretty serious people.
"The Gambit of Morphy, Anderssen, Steinitz, Bronstein, Spassky, Morozevich, and Shirov, of course--the King's Gambit!"
Name one Queen's Pawn player who has not played the QG.
"There is no opening with a richer history of providing an avenue for good, classical, attacking chess than the King's Gambit!"
Agreed.
"1. The Queen's Gambit is not even a gambit!"
Yeah, so?
"2. Compared to the King's Gambit, the Queen's Gambit is boring!"
True, compared to the KG, the QG is more like a lame sibling in terms of speculative chess, but on its own, the QG is a complex opening, rich in resources and ideas, and it is anything but boring.
"3. Black decides where the game is headed in the Queen's Gambit, whereas White decides where the game is headed in the King's Gambit!"
What the hell are you talking about? Black can decline the QG, but so can he in the KG. Black can take the pawn in the QG, and so can he in the KG. Black can counter-attack the QG with the Budapest, Chigorin etc, but so can he in the KG, such as the Falkbeer, or other more seldom seen moves like 2...Qf6.
"Pretty clear-cut choice, don't you think?"
No, if anything, your arguments turn upon itself.

I was not kidding
The King's gambit was a strong oppening, but now players know how to deal with it.
Look at Chess.com masters database and see that while the QG was played 81.070 times, the KG was played only 4.529 times.
1.e4 e5 2.Nf3 was chosen 113.951 times, so 2.f4 is not a good option, I guess...
After 2...exf4 black scores better than white in the database.
Of course, among amateurs, like us, the King's gambit may look well, but the question was not about low level chess. By the way, even in low level, I guess the QG is better.

"Look at Chess.com masters database and see that while the QG was played 81.070 times, the KG was played only 4.529 times."
What I see in the database is that with the KG, white wins about the same as, or slightly more than black, but the draws are minimal.
In the QG, white wins much more than in the KG, but draws are even more frequent than wins.
So, basically the QG is safer for white.

"Whichever one you can play better, no."
Exactly, Lisa., I feel the same way. And we might add whichever suits your temperment. Some people love the gambit tightrope, others avoid it like the plague.

One's a real gambit; one's a pseudo-gambit. There's no comparison.
I agree - QG is not really a gambit.

Queens gambit is safer and though the development may be sometimes slow and positional,white gets a firm grip on the game,castles develops his queen at c2,Bishop to d3 and then attacks.i prefer this.
My brother sometime played in the national tournament.He was the onlyone who played this line.But as he played higher boards and tight players,he lost with this.
The KG gives away a pawn for development and initiative (and possibly to help control the center) with no thought of winning back the pawn (in fact in some variations, white also gambits a piece, even two, in addition) and is a true gambit. The QG offers a pawn with the knowledge that if the pawn is accepted, it will be reclaimed, so it's a pseudo-gambit.
^I agree with this. I like King's Game for the funny tactical play that ensues.
I like the Queen's gambit better.