I think the reason Fischer favored 1. e4 was because it tends to lead to middlegames with more tactical opportunities. 1. d4 is considered a slower opening, favoring pawn structure over early tactics. -Although arguable, we’re talking at the grandmaster level. At lower levels, any opening is full of tactics.
I personally favor 1. d4, since I like to be able to control the pawn structure, looking for tactics, but also looking for ways to just get a small advantage over my opponent, so that if i do get to the endgame, I’ll have an advantage. On the flip side, if I slip up or miss something and my opponent gets an advantage over me, then its hard to get the advantage back.
As black, I tend to favor highly unbalanced tactically rich positions. I like to respond to 1. e4 with the Sicilian, sometimes the French.
-I got tired of the French as of late though, since its impossible to avoid the drawish exchange version.
Against Unzicker and Zerquera both games started out as 1.e4 e5 2. Nf3 Nc6 3. Bb5 Bc5 4.c3 Nf6 5. d4. With Zerquera, Fischer responded 5…exd4 with a draw in 30 moves, against Unzicker, Fischer played the more conservative 5…Bb6 and the game was drawn in 17 moves.
In his game with Spassky Fischer decided to hold on to the pawn with 1. e4 e5 2.f4 exf4 3. Nf3 g5 4. h4 g4 5. Ne5 Nf6. Spassky’s attack on the kingside proved successful.
Gilgoric’s game was very similar to Zerqura, and ended in a draw in 20 moves.
Fischer deviated from the other Ruy Lopez’s with his game with Tal by plaing 4…Nge7 instead of 4…Nf6 leading to an active game 5. d4 exd4 6. cxd4 Bb4+ 7.Bd2 Bxd2+ 8. Qxd2 a6 9. Ba4 d5 10. exd5 Qxd5 11. Nc3 Qe6 12. Kf1 Qc4+ 13. Kg1 O-O. However the game still ended in a draw in 29 moves.
Mendis’s game was a Guiano Piano 1. e4 e5 2. Nf3 Nc6 3. Bc4 Bc5 4. c3 Nf6 5. d4 exd4. Mendis pushed a passed pawn, but was lost on the 40th move after nearly all the pieces were traded off. Fischer then converted a knight and five pawns versus knight and four pawns endgame.
Addison’s game was another Ruy Lopez 1.e4 e5 2.Nf3 Nc6 3. Bb5 a6 4. Ba4 b5 5.Bb3 Na5. Fischer initated pawn storms on both the queenside and the kingside, and with two seperate threats was able to win a pawn on the 34th move. White resigned four moves later when a second pawn was lost.