I have tried all three of them and the BTV and Shava TV are very similar. I find the Shava to be less reliable vs the Jadoo and BTV but the channel selection is very similar on all 3. I'd agree that the Jadoo has been on the market the longest and seems to be the most popular choice for Indian tv programming.
Shava would be my least favorite of these 3 boxes and Jadoo and BTV are both equal.