I'm vitamin D deficient. Is there a particularly good supplement I can take?

My doctor just prescribed 50,000 units of vitamin D2 to me today (7 pills, one per week) because I’m well below where I should be for vitamin D levels, and then I have to switch to 2,000 units per day.

However, after doing some research, I realized the general consensus among doctors is that D3 is preferred over D2 to actually make a difference in deficient patients, but that D2 is often prescribed because it can simply be really difficult to find D3 in high enough doses that will make a difference in someone as deficient as I am. The drawback, apparently, is that D2 might raise your levels, but only very, very shortly – which defeats the entire purpose of being placed on such a high dose to begin with, and some people even claim that D2 can have some negative health consequences.

So… although I’m going to follow my doctor’s orders, I would like to find a 2,000 unit supplement, but in D3, not D2. Is there anyone here who was really deficient, took D3 supplements and saw a difference in levels after a blood test? If so, what brand did you take?