d2h has good picture quality...only some channels have pixlation..
about dish tv more people say that only HD is good and SD is pathetic.(i had a dish tv 2 year back , during that time PQ was very very pathetic .. i felt pixlation even in CRT tv, cant say about current quality ) . check current PQ and decide.
Tata sky has clear picture but not sharp .(it is due to deblocking). Tata sky aplies too much compression in both SD and HD channels . i would reccomend to not buy a TATA sky as their users are crying for channel addition .
Airtel's PQ is more or less same to D2h (in 32") bcoz both applies less compression .(no compression in HD channels ).
So have a look on package of Airtel and D2h take that which suits you .