Here's my rule of thumb: if my search doesn't depend on recent information, and it is likely to return blog spam as the top result, then I will use ChatGPT instead.
I still use web search frequently to find project homepages, official and up-to-date documentation, news and announcements, discussion (hearing people's stories of their experiences with a product is a lot better than ChatGPT's noncommittal and abstract pros/cons), searching for videos/images, etc.
GPT 4 just got browsing, so I've actually started telling it to do the entire research phase I was gonna do and just let it grind it out without having to despair at Google's abysmal search results. Still a bit unreliable but actually gets it done quite well on occasion.
I still use web search frequently to find project homepages, official and up-to-date documentation, news and announcements, discussion (hearing people's stories of their experiences with a product is a lot better than ChatGPT's noncommittal and abstract pros/cons), searching for videos/images, etc.