Generally speaking, both text messages (SMS) and WhatsApp messages are generally safe, as long as proper security measures are taken. However, messages sent via WhatsApp are generally safer, as they are encrypted end-to-end. This means that only the sender and receiver can read the messages, so they cannot be intercepted by third parties. Text messages, on the other hand, can be easily intercepted and read by anyone with a bit of technical know-how. Therefore, in terms of security, WhatsApp is the better option.