Best format of laundry detergent for my needs?

After trying to jump from detergent to detergent, I’ve gotten two new detergents to try and they seem to be my top two picks. However, one is a powder and while it seems impressive, I have never used powder before. My main question is: which is better for my needs, a liquid or a powder? I primarily wash bright and intense colors, always in cold (with the exception of undergarments, which go in warm or hot) and I have an older, agitator-type washing machine.