Happy to recommend https://pinafore.social. It's an excellent Mastodon client for web. Some highlights:

- It's really fast (loads quickly, smooth scrolling, handles spotty network connections well).
- Responsive across devices
- Works offline. Installable Progressive Web App
- Surprisingly featureful w/some ideas I haven't seen in native clients just yet.

You can also read more on the technical details, like its use of Svelte and CSS Grid: https://nolanlawson.com/2018/04/09/introducing-pinafore-for-mastodon/. Kudos to @nolan