David Silva was my favourite player ever when he was with Valencia, I thought he was mesmerising to watch without being flashy and when we signed him it was one of my best days as a City fan of 45+ years.
I think he was at least the equal of both Xavi and Iniesta and personally would say that he was better than both.
Xavi and Iniesta were arguably surrounded by better players in their prime in a much weaker league. David could do what they did while having lumps kicked out of him and then would dish it back out to the cloggers in spades. If Silva had played in Spain he would have been much better utilised by their national team I suspect and his greatness would be better recognised.
For me David Silva is the greatest attacking midfielder this country has ever seen bar none.
In reality, this is a bit of an unwinnable argument as all three players were some of the best in the world but all had varying skill sets with different pros and cons to their game, meaning they would work differently in each team.
Attempting to definitively decide 'the best' is a fools errand but there's only 1 I'd sell every single thing I own to see play on the Eastlands pitch one more time.