what is the best opening for black and white for around 1000 elo players
A system probably is best... upon taking up a system... you learn how to thwart your opponet's attempts to to take you out of your game.
If you are asking this, it is a safe bet you are not some chess prodigy, so you won't be playing super GMs . Below 2500 elo... outside so suspect gambits... a system will do what you need it to.
I.e. Get you into familure positions in the middle game.
Unless you star playing in state tournaments, national opens...
1.d4 d5 2.Bf4
Against e4 play Caro which is c6
Against d4 play Nf6
At that level I recommend trying the Scandinavian defense for black, and the London system, King's Gambit, or Italian opening for white. Just staying solid to get familiarized with the fundamentals of chess and setting up an attack.
For a system opening I think I'd recommend the KIA over the london. I don't think your opponents will know what the KIA is at that level.
Black... maybe the Slav. Your opponent is just going to let you get your bishop outside the pawn chain and fail to reclaim the pawn probably.
Against e4 I'd probably just stick with e5, it's a good way to learn chess.