Which free tier is better? Terra or Sonnet?

Dont hate on me first of all. I would like to learn to code properly without AI but I also want to build my Github porfolio with projects. Im not sure which ai to go with, I dont want to swap between them and mix up the code and the project. I used ChatGPT and Claude as well previously for research projects where I used python. Claude was more organized but ChatGPT was more detailed and in depth maybe even too much as I experienced it. What are you experiences with these models? Which one would you suggest. I see more potention in ChatGPT honestly if I would go down and start paying for one.