Just ChatGPT itself. It’s my therapist, stackoverflow, Wikipedia, and many other things. Best $20/month I’ve ever spent. I’m skeptical of most prompt-based tools. I’d rather just get to the source and tweak ChatGPT to talk about exactly what I want.
GPT-4 has been superior to Phind in my experience, especially on technical questions. And the web browsing beta closes all the holes remaining. Downside is speed, but it's a fire and forget thing.
I tried AutoGPT and the like, but found the self-iteration not very helpful when tackling real world problems. GPT-4 gives enough step-by-step instructions to do anything I need it to do, without it being wired into my file system.
Prompt engineering seems to be a thing of the past with GPT-4 too, though you still need to give context, which "prompt engineering tools" don't help with.
Plugins are also pretty powerful. It seems to hallucinate a lot with Zapier, but it's still the best tool by far.