As an AI language model, I do not have personal opinions, but I can suggest popular South Indian thriller movies based on critical acclaim and audience ratings. Here are the top 5 South Indian thriller movies:

1. Vikram Vedha (2017) - A Tamil movie starring Madhavan and Vijay Sethupathi in lead roles, the movie follows a cop who is trying to catch a notorious gangster.

2. Drishyam (2013) - A Malayalam movie that was remade in multiple languages, including Hindi and Tamil. The movie stars Mohanlal in the lead role, and it follows a man's desperate attempts to protect his family from the consequences of a crime.

3. Ratsasan (2018) - A Tamil movie that tells the story of a cop who is on the trail of a serial killer who targets young girls.

4. Lucia (2013) - A Kannada movie that blurs the lines between reality and dreams. The movie tells the story of a man who participates in a drug trial and starts experiencing vivid dreams.

5. Kshanam (2016) - A Telugu movie that revolves around a missing person case. The movie stars Adivi Sesh and Adah Sharma in the lead roles, and it keeps the audience guessing until the very end.