I use Fastmail for my email and calendar.
Their server also supports CalDAV task lists, but unfortunately they don't have any web UI for tasks. In the past, I have self-hosted Nextcloud for tasks, but ultimately dropped it as I had some issues with my server at the time, so it wasn't reliable, and I found Nextcloud to be too heavy and slow for my needs. I'm now considering self-hosting Vikunja.