I tried perplexity.ai for first time yesterday, and was impressed by it. While it uses GPT 3.5 it's not exactly comparable to ChatGPT since it's really an integration of Bing search with GPT 3.5, as you can tell by asking it about current events (and also by asking it about itself!). I'm not sure exactly how they've done the integration, but the gist of it seems to be more that GPT/chat is being used as an interface to search, rather than ChatGPT where the content itself is being generated by GPT.

Microsoft seem to be following a similar approach per the Bing/Chat verson that popped up and disappeared a couple of days ago. It was able to cite sources, which isn't possible for GPT-generated content which has no source as such.