I don’t like the duck.ai interface much (choosing a different LLM is not easy once you’re already in a conversation), but I use it a lot more than I use the DuckDuckGo search engine (the results from the latter aren’t great).
Just like with DuckDuckGo search, where I start a search and then use the !g bang command to go to Google for better results if needed, I try duck.ai and then move to ChatGPT (without any account) when even the best models in duck.ai aren’t good enough.
For most simpler queries though — where I’m just looking to learn a bit about something as opposed to finding a solution for a specific (more complex) question or problem — duck.ai with its GPT 5 models are more than adequate (even the 4o mini is fine).