I’ve used both, currently back to Google. No real experience of speed difference between them.
If you have slow WiFi, are you using 2.5GHz or 5GHz access point(s)?
If ‘WiFi’ is slow, it is usually your router, or configuration of it, and maybe it’s positioning within your environment.
If ‘Internet’ is slow, then that’ll be a question to ask your ISP - what speedtest results do you get (speedtest.net)?
I use it because it is a little bit faster (requests are served in London and Manchester whereas Google respond in Belgium), privacy and DNS updates instantly for my sites because I use Cloudflare for them
I mean DNS services are in the milliseconds these days so I’d doubt you’d feel a difference unless you are using a really bad ISP one that essentially timeouts few times until it finally brings a response…
Used to use the google one, moved to Couldflare for privacy reasons too…