A wellcut diamond will show very little warmth face up til you get to below a J. Face down is how they're graded, and where you see the most body color. A side view will also show some body color. Obviously side by side, if you held a D to a J you'd see some internal warmth but definitely not yellow. However, diamonds reflect their surroundings, so unless you're in a perfect, stark white vacuum of color, it's going to pick up what is around it.
I have currently and have in the past owned stones as low as a K, my sweetspot seems to be an H. Just enough warmth to liven it up, but not warm enough to not read super white. And yes you do get a better value for the price from H-J, though they're gaining popularity as people want more bang for the buck.
Focus more on cut quality (which you should surely see with WF) and then decide if color or clarity is more important. For ME it's always clarity.