There is no such thing as best palnet as per astrology. There rae nine planets including Rahu 7 Ketu and excluding Uranus,Neptune & Pluto.Any or all the planets may be good or bad as per the individual's horoscope. also any planet can be good for a certain event of life and bad for the other event of the same native.
Just taking an example in the system I follow if Sun's dasha is running and Sun's cpo ordinates are 1,6,10,then it is perfect for the carreer of the native but worst for married life. Both the things will be experienced at the same time.
However Venus if with good co ordinates is a very good planet and the indicator of something new and very good.
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There is no planet as such best and worst.It all depends on the planetary positions. every position has its merits and demerits. Generally Jupiter is the most benefic planet and least harmful. it is described as God\'s grace. significator for wealth,children.divinity etc