Which coffee bean machines are very demand in market ?
Seeing as you're in Delhi, I did a quick Google and you can source La Cimbali, Astoria and Expobar easily enough it seems. All of these are good brands.
Still not really sure what your question is though. What coffee machines are in high demand, as in what do most cafe's want on their bench? In Australia at least it will be something outlandish and showy to outdo the neighbour cafe or something well proven and capable. The La Marzocco brand is probably one of the most popular, not sure if you can get them in India though.