1st opening is Queens gambit. as a d4 player the best opening is either the Slav or the queens gambit.
The reason why the gambit is so good is because it just works I study my theory and I just cook all my opponents even if they do something goofy like englund gambit or the Dutch.
I just cook them by just being good.
Guico Piano game is one of the funiest openings to play as black. Its pretty solid and it works extremely well in general.
The reason why this opening is good is that its just an overall good opening and its one of my opening that I studied and can take the advantage over my opponent.
Overall I think this is just a good opening to know in general and I love it.
Evans gambit is a variation of Guico piano or ruy lopez but its different my opponent tries to bait me into making this mistake and that mistake and it just works for me.
I enjoy it overall and I think its an important one to know how to abuse and learn to not get cooked.
Englund Gambit is one of the best to play against a d4 player. I think many people don't study it or they study it if black makes a mistake and I studied both because it works well against d4 players.
I love it since its just op against dumb d4 players.