what type of vfd control is most reliable..dipak chavda

Your question requires more specifics. Voltage source or current source? V/Hz or vector? Application? Environment? Etc.

"Reliability" from an engineering perspective is a function of the reliability of each component multiplied by the number of components, so the simplest answer is the "simplest VFD with the highest reliability components." But each application has its own peculiarities, and what might work acceptably well on, say, a building ventilation blower would not survive long operating a material conveyor.

Please clarify.

Kevin is correct, as you need to explain your Application &/or what the Enviorment is ?
The details about the Voltage & Current Source could be important, as well as the Motor info if existing .

As explained above in all the responses, application engineering is most important to decide upon best product for best application

Completely agree with Kevin and Ray. Every VFD has its peculiarities and site application is the point which should be put into consideration for selecting VFD brand.