D3 is better than D2 (D2 is the precursor that turns into D3 in the blood) - it is usually suspended in oil. If you've had gastric bypass or have colitis, or similar dysfunction where you don't absorb oil, it's better to do the dry form. You can get the dry form from the manufacturer directly (not overly expensive) -
http://bio-tech-pharm.com/
Most everyone is short vit D, which is actually a hormone.
I can recommend bio-tech highly.
alys