WeChat is owned by Tencent Holdings Limited, a Chinese company. Most Chinese companies are owned and controlled by Government of China. Considering allegation of espionage on some Chinese companies, I really don’t trust products from Chinese companies. Moreover they don’t believe in innovation rather they believe in copying. Most of their applications remarkably resemble products of their competitors. No one knows what security measures they take to protect your personal information.
On the other hand WhatsApp is owned by US based Facebook Inc. the company may peek in your personal data for their commercial benefits but still they are more secure. There were a few security flaws in past but recently WhatsApp has tied up with Open Whisper Systems for end-to-end encryption by incorporating the TextSecure protocol.
