D40 Sigma 50-150 or 70-200?

Good morning,

I have a D40 which I have learned a good amount with, and am feeling comfortable shooting with. I have the kit lens and the 50-200VR which were good, but as with everyone else around here I started to thirst for more.

I then bought the Sigma 30/1.4 which was an incredible upgrade for the camera. I noticed a huge difference in my photos and am now looking to upgrade the upper zoom range. I can't afford the Nikon AF-S 70-200 2.8 so I am again looking at the Sigma's.

Should I go with the 50-150/2.8 or 70-200/2.8? (obviously looking at the HSM for my camera) . I understand the differences in zoom range, so specifically, as far as IQ - what is my best option between the two (assuming they both work on the D40 which I am pretty sure of).

PS - Am I missing anything else I should be looking at also?