what is a kumite for shito-kai karate ?

What is  Shitō-ryū
He is direct student of Soke Kuniaki Nobukawa (JKF Hachi Dan and the founder of Japan Karate-Do Nobukawa-Ha Shito-Ryu Kai).
Which is best style of Karate Sotokan, gosoku ryu karate?
There is no best style, it all depends on the practitioner and the way its taught. Choose the place with the best instruction regardless of style.

Sparring in karate called kumite. This literally means "meeting of hands." Practiced both kumite as a sport and self-defense training.Kumite Strategies. Attack is the best form of defense (Ukete wa Uchite)
Levels of physical contact during sparring vary greatly. Full contact karate has many alternatives. Knockdown karate (such as Kyokushin) uses full power techniques in the development of discount on the ground. Kickboxing variables (for example K-1), and win by knockout is preferred. Sparring in armor (bogu kumite) allows full power techniques with some safety. Sport kumite in many international competitions in the framework of the World Karate Federation is free or structured with light contact or contact semi-points are awarded by the referee.
Structural in kumite (Yakusoku - prearranged), two participants perform a series of techniques failed with one hit while the other blocks. Form ends with one method destroyer (Hito Tsuki).

In free sparring (Jiyu Kumite), and participants are free to choose scoring techniques. Is determined primarily on the techniques permitted level of communication through sport or style organization policy, but may be modified according to rank and age and sex of the participants. This also allows stops, similar to campaigns, and take downs, and in some rare cases even a limited time grappling on the ground.
Free sparring is performed in an area marked or closed. Runs the game for a limited time (2 to 3 minutes.) Time can run continuously (IRI Kume) or be stopped for Democratic Governance. In light contact or semi-contact kumite, points are awarded based on the criteria: good form, sporting attitude, and powerful application, awareness / zanshin, timely and correct distance. Kumite in karate full contact, and points are based on the results of the effect, not the formal appearance of the scoring technique.