It's a matter of taste. If people want a shortlist, I'd say Tusky and Fedilab on Android or Toot! and Ice Cubes on iPhone.
There's also Megalodon which is good but the dev still describes it as experimental, so I don't know what their long term plans are?
And then there are polished apps like Ivory but that is a subscription service.
At least on Toot! you can scroll to the top of the timeline by tapping the very top of the screen?