In my knowledge dish tv pic clarity is >>>better than tata sky for both SD & HD.
tata sky more hd channels but compressing more.
dish tv less hd channels better PQ.
Currently I am using tatasky hd hevc t 51 brother and it's suscription coming to end soon my family members watch only Hindi entertainment hd+ sports hd channels only if I suscribe this channels in tatasky they are very costly comparing to dish tv