I've used Freshbooks for invoicing for years, and I've switched between their time tracker and other services/apps repeatedly.
Switched to timely first of August, and I'm still happily using it even though it increases my pain significantly a couple times a month when I have to invoice things--timely is just that much better for scheduling and tracking that it's easily worth it for me.
While I'm here, I would love if the web app had a multi-week view so I could plan a month more easily and drag tasks between days over larger spans.