I use Electrum as a watch only wallet both on mobile and laptop/desktop devices. It's fast and responsive, and I absolutely love the clean simple interface. It was great 10 years ago and it's great today. :-)

I've recently started using Sparrow wallet, and I'm getting to like it more and more, it also work very nicely as watch only, with the cool advantage that can connect to my own node without the need of an Electrum node.

I also use Bitcoin core as watch only on the CLI, of course, much faster and much more responsive than any graphical wallet. :-)