TBH both the brown color and black which i see from the pics look good on you. I'm kinda more leaning to the brown one though, looks more fitting on you to me.
But i would say don't give it that much attention, your beauty is in your eyes, most guys (especially the ones who like pretty eyes) won't even notice your hair color. This is true story. I am not just saying this from my mind, it's something im relating off myself. If i was to meet you for example i wouldn't really care or even notice much your haircolor because i am too busy staring and admiring your eyes.
Your natural hair color. I dont know why i have to keep telling people this but there is only one time when a women should dye her hair and that is when its turning gray in odd spots. Trust me, its such a seventh grader thing to do. You want to attract real, mature men than start looking like a mature women. Im not trying to be an ass hole but i just know that i find hair dyeing a real turn off.
Your natural hair suits you best, it will always look good and will never go out of style.