PaaS or IaaS : Which one do you prefer and why?

I am building a Java app and I want to make it live quickly. I don't have much experince with DevOps as well.

I am considering hosting it on Heroku. As it is very expensive, I am considering using DigitalOcean or Linode or AWS. Again, as I am very new to DevOps, I don't want to take risks and waste much of my time making app live.

Which one should I choose and what are the pros and cons of each?