So sorry I was not available yesterday. Anyways I will declare the results. Bc2: 7 votes. d4: 1 vote. The winner is Bc2 and given that and stockfish responds c5.
lichess.org/Wuk2XBl0 Tell best moves now.
b4 or d4 Dark colored bishop is sleeping
d4 is book. b4 is bad, forcing knight back into the game.
D4 to
1. Bring bishop out
2. Control space, Black is already enjoying half of the board.
3. In opening, first goal is to play central pawn moves whenever get a chance. Delay will make it more and more difficult.
B4 is bad
1. Black won't exchange at b4
2. Threat of C4 is greater making queenside cramped
A4 is bad too
1. X-Ray attack by Ra8