I strongly think PETROV DEFENSE is the best.

Chess isn't an art. Chess is a war.

1. e4 e5
2. Nf3 Nf6

opening chess moves
The move 2...Nf6 was first investigated and brought to the attention of the chess playing

This opening has a reputation as a remis variation and being boring. You can avoid the Petrov as White if you start your first moves like this:
1.e4 e5 2.Bc4! Nf6 3.d3

If you play the Petrov as Black you can avoid the Ruy Lopez (Spanish Opening), the Italian Opening and the Scotch Opening.

The classical move for white is 3.Nxe5. After that Black has to chase the white knight back with d6!, before he attacks himself and takes the white pawn on e4.

So, don't take the other pawn with 3...Nxe4? right away as this is bad as White will get the superior position after 4.Qe2. This variation is explained below.

chess opening
1.e4 e5 2. Nf3 Nf6 3.Nxe5 Nxe4?? 4.Qe2 Qe7
opening chess moves
5.QxN d6 6.d4... 6...dxNe5 7.dxe

7...Nc6 8.Bb5 Bd7 9.Nc3 0-0-0 10.Bf4 and White is a pawn up.

My favorite game of Petrov Defense

Karjakin, Sergey - Jobava, Ba 1-0 (2016)
1. e4 e5 2. Nf3 Nf6 3. Ne5 d5 4. ed5 Qd5 5. d4 Nc6 6. Nc3 Qd4 7. Nc6 Qd1 8. Nd1 bc6 9. Be2 Bd6 10. Ne3 O-O 11. O-O Re8 12. Bf3 Bd7 13. Nc4 Bc5 14. Bf4 Nd5 15. Bg3 Bf5 16. Ne5 Bc2 17. Rac1 Bd6 18. Nc6 Be4 19. Rfe1 Bf3 20. Re8 Re8 21. gf3 f5 22. Bd6 cd6 23. Kf1 a6 24. Rd1 Nb6 25. b3 d5 26. Nd4 g6 27. Rc1 Nd7 28. Rc6 a5 29. Rd6 Ne5 30. Rd5 Nd3 31. Ne2 Re2 32. Rd8 Kf7 33. Ke2 Nc1 34. Kd2 Na2 35. Ra8 Nb4 36. Ra5 Nc6 37. Ra4 Ne5 38. Ke3 g5 39. h3 h5 40. f4 gf4 41. Kf4 Nd3 42. Kf5 Nf2 43. h4

I used it about 1 years ago , when i started playing OTB tournaments. Despite being functional i just can't get used to his lack of counterplay and attacking chanches.
So i briefly switch to sicilian sveshnikov which accompany me for most my OTB experience.
Now i play the Scandinavian Qd8 system, while being solid as the petrov it has some dynamic possibilities which i didn't found in the petrov system.

As far as I know „Superrussisch“ („super-Russian“, 3. ... Nxe4) is far from clear. No particular big advantage if at all.

#4 Correct. If they want to bore you to death, bore them to death, first!

And yes, 3. Nxe5 Nxe4 is far from being refuted.

I can never resist playing the Cochrane gambit.

In the Petrov opening the first player who falls to sleep will lose the game

@Sarg0n Yup, it's a very annoying line to face actually. If I remember correctly, the most critical line is the one where White castles long. It leads to an interesting endgame where White has rook and 2 pawns for Black's 2 minor pieces.