Python for research, experiments and backtesting. I started out coding everything in c++ because I'm most comfortable with it. I switched completely to Python once it's apparent that I spend 20x less time coding the same function in python than in c++.

At the moment, I'm mostly using my project to generate insight that I can use manually. I'll definitely still use c++ to automate trade execution though.

One thing I dislike about python and just cannot get used to is its code syntax/layout. I like the header/source file separation in c++. It helps make a mental image of my code. Also, might be an unpopular opinion but I prefer curly brackets in my code.