This is not such a simple answer, I am presuming that you mean "what is better for self-defense or fighting effectiveness"? Let's be sure you know the difference between what is popularly termed "wrestling" and "kung fu".
Wrestling can be any manner of grabbing, throwing, pinning, locking, and holding an opponent. It is known for it's tight or close in fighting. Wrestling serves as mankind's most natural way of fighting or defending (evolutionarily speaking, we have certain instincts hardwired in us that came from our simian ancestors and can still be seen as a means of fighting by almost every known primate) and was used by every army on every field of combat when a weapon is no longer useful or lost during a fight between combatants.
Wrestling can be a term to relate to the oldest form of fighting as showcased in ancient carvings and art. There are many forms of wrestling. Nowadays, the word "Grappling" is also used to convey "wrestling", fundamentally they mean the very same thing. Jujitsu is a style of wrestling from Japan. Pancrese is a style of wrestling from Greece, Sambo from Russia. Dumog is from the Philippines. Malla-Yudda comes from India. Guresh from Turkey. Glima from Iceland. The list goes on and on.
Mixed Martial Arts (MMA) is full of wresting methods. "Pure wrestling" such as "Greco-Roman Wrestling" (such as practiced in High schools, Colleges) is devoid of striking, while more ancient forms suited for combat also taught striking (punches, kicks) within the core of their wrestling art. Wrestling can also mean the popular drama/action in a wrestling ring that uses made-for-entertainment personalities such as "Hulk Hogan" and Dwayne Johnson formerly known as "The Rock".
Kung Fu (Mandarin) or Gung Fu (Cantonese) meaning "Skilled Effort" has many manifestations ranging from stylized discipline, self-defense, combat, health routines, and sport. In fact it would be difficult to pick out the difference of techniques between many Kung Fu and "Wrestling Styles" if no indicator (uniforms, signature positions) were given to the observer. Kung Fu may be called Wu-Shu (Martial Art), and Gou-Shu(National Art_, or simply refered to Chonese people as "Chuan/Quan/Kuen" meaning Fist or Boxing. They all can be referred to as Chinese Martial Arts (CMA). Within the pantheon of CMA, there exists sub-systems and whole systems of wrestling techniques. Chin-Na(Mandarin) or Kum-Na (Cantonese) meaning "Seize-Control" are found within most Kung Fu systems such as Wing Chun, Tai Chi Chuan, and Shaolin. Then there are Systems such as "Shuai Jiao" (Trip/Fall Wrestling) and "Kuai Jiao" (fast wrestling) have many popular forms and is useful for self-defense and also as a sport. Many systems of Kung Fu also incorporates techniques of Shuai Jiao and Kuai Jiao methods. Many Shuai Jiao/Kuai Jiao systems are taught incorporating CMA styles also.
Now, in terms of effectiveness, in skilled hands both "Wrestling" and "Kung Fu" can be very effective and useful in self defense. It really comes down to what may suit your personal needs and also your proclivity and preference. I suggest starting with a teacher that knows both ways of fighting- strike-oriented and wrestle-oriented abilities. Both are mutually enhancing and can be synchronized such as they give harmony and rise to one another.
In self-defense what matters most is what gets you out of a bad situation and back to safety or protection. Wrestling generally has a tendency to go to the ground, while Kung Fu generally stays upright. In all self-defense situations you may think you are facing one attacker when you may get surprised by additional attackers. Kung Fu has specialized in handling both individual and multiple attackers. Some wrestling systems Pankration (Spartan Martial Arts), and Japanese Ju-Jitsu such as Daito Ryu Jujitsu or Aikijutsu; have specialized in multiple attacker skills.
In all of my decades of experience I would say be open-minded, do research, and fall for no hype or urban legend. If we are indeed, speaking toward keeping you a safe person and possibly allowing you to protect others it is no time to make immediate commitments, all I do know is that finding a good teacher that understands both and bases what he or she may teach on straight forward, unbiased, scientific, and proven methods is the way to go. There are many "Meet Ups" in local areas that may be a group of different stylist and by working out with them you may develop a higher perception of what it is that you are looking for and do so with good information. Best wishes in your Martial Journey.
