What is the most sound gambit or counter-gambit

Besides the Queen's Gambit (white can get the pawn back right away when he wants)  I would say the Benko Gambit.  Lots of positional compensation.  Not just hoping for a quick attack or a blunder

1)budapest gambit

2)albin counter gambit

3)falkbeer counter gambit

especially budapest gambit

@koala8 Wow that Budapest gambit game you posted was a bloodbath.  Straight to the endgame!

I was only showing main lines and mistakes opponents can make

The Scandinavian Gambit 1.e4 d5 2.exd5 Nf6 3.c4 c6 4. dxc6 Nxc6 gives Black some positives assets for the material invested. In fact, I read somewhere that Grandmaster John Emms, in his book "The Scandinavian", go as far to gratify a interrogation mark (?) on 4.dxc6 and writes something to the effect that: "White's greediness will leave him in a miserable position for the remainder of the game thanks to Black's sudden iniative and great central control."

Not sure that's the exact wordings since it's quite a while I read that comment.

@Fralnp.  I play the Scandinavian Modern/Marshallvariation (Nf6) as my primary response to 1. e4.  That is my favorite gambit in the Scandinavian defense: the Panov Transfer.  I always pray my opponet plays those moves.

Black Gets tons of development and initiative as compensation for that one extra wing pawn.

http://www.chess.com/opening/eco/B01_Scandinavian_Defense_Panov_Transfer

Albin shouldn't be considered sound.

4. Open Catalan

5. Semi-Slav Anti-Moscow Gambit

6. Exchange Grunfeld with Nf3+Rb1

Yes, but sometimes my opps. generally follows with 5.d4 so I don't have the chance to always play this sharpening line...

Anti-Meran Gambit.

I'm curious about the Budapest's status as a gambit. Not its soundness as such, but whether it is a gambit at all.

Are there any 1.d4 books or strong players that advocate keeping the pawn for White (ie the 6.Nc3 line)? It seems that most of them agree that White is better off in the other lines.

It is technically a gambit it gives away material without receiving it back immediatly

it is a real gambit black can't forceably get the pawn back but giving the pawn back is reccomended

Right that is my point, White returns the pawn quickly.

The difference between the Budapest and other gambits (Marshall/Benko/Albin/BDG) is that the second player is advised NOT to hold on to the extra pawn .

So, if anything, when played as a gambit it is better than most of the other gambits...

its funny because the budapest gambit isn't good

I agree that the Marshall Attack vs the Ruy is strong.  I used to play the Budapest. It can be effective, but I believe with best play White will be better. I read somewhere that White should play 4. e6!

Scotch Gambit is good.