We have been using UptimeRobot, which is quite good, but things can always be better. We also use a self hosted statping instance, which is able to do more than UptimeRobot, but can be difficult to configure. It also lacks project-centred status pages.

Enter Better Uptime. This has
- users
- project-based whitelabeled status pages (though they do have a 'powered by' thing)
- fast 30 second checks
- the ability to add a cool off period in case of flaky connections
- checks by either status (2xx) or keywords
- ability to schedule on-call time for users
- heartbeat monitoring for scripts

I did have some problems when initially setting up some (specialised) monitors, and I have reached out to Better Uptime to see if it is User Error on my end (probably!) or if there is something missing still.

So far, my impression is very positive and this product is off to a great start!