First question - any windows? If you have no natural light, or very limited (small windows) and you do not really want a cave, you probably want to keep the walls on the lighter side, and white or a light ceiling tile will also keep it from becoming too dark a room. A dark ceiling especially if it is fairly low which most basements are has the effect of making the room feel more confining. It is a pretty long space and it would make the whole space feel longer, narrower, and lower.
Walls - The floor you choose is likely to be a fairly neutral color, so I would choose your wall color first - what is going on the walls, and does any of it have a predominant color - if so think about how you want to contrast to that. Dark colors will again tend to shrink the room. Nothing says all the walls have to be the same color - lighter colors on the long walls will make the room feel wider. while a dark color on one of the shorter walls would make that wall feel closer, making the whole room feel more square. The darker the walls, the more confined the space will feel - if what you want is place for you to spend time at a desk, reading a book, or watching TV by yourself or with a few friends, you may want that confined feeling. If it is a more social space or if you like feeling expansive, lighter will be better.
Flooring - if you do have any windows, light reflecting off the floor will brighten the room and so the lighter the floor the more reflected light and the brighter the room. That is true for electric light as well so even with no windows, a lighter floor will tend to make the room feel brighter. At the same time, too light a floor can make the room feel 'ungrounded' - personally I would go for a mid-range darker than whatever you choose for your walls, but allowing some reflected light to fill in.
In our natural world we see a dark earth beneath our feet, a mid-range tone of objects at eye level and a bright light sky so there is a psychological rightness to that sequence - dark shoes, medium dark trousers or skirt, lighter top. It is a little jarring to see white shoes or light trousers/skirt and a dark top - it makes a statement that can be effective, but definitely stands out and can look really odd. We react the same way to rooms we walk into. A light floor with a dark ceiling and walls can be uncomfortable.
Finally - a practical thought - the easiest and cheapest change you can make is wall color. If you go neutral (browns or grays) on the floor, and neutral on the ceiling, a few cans of paint and a few hours with a brush and roller can completely change the feel of the room a few months or years down the line. If resale is a real consideration for you, traditional darker floor, light or white ceiling makes sense - put whatever personal stamp you want into the wall color which you can repaint to neutral prior to putting the house up for sale.
