I use the standard $20/ChatGPT Pro sub, and run Thinking 5.5 as a chat interface.

I use it like a "trusted personal advisor," as opposed to a "black box employee."

I'm intimately involved in almost every step of the development process. Most of what I ask from the LLM, is function-length snippets.

It's made a huge difference in the velocity and scope of my work.

I have learned that I need to be very careful, though. The LLM sometimes really borks things, and I have to rip out the garbage, and rewrite the code, myself. I can't even imagine the quality of "vibe-coded" software.