Liftoff is as close to RIF in terms of function I have found so far (especially with the last update adding comment context buttons), but I am also waiting on Boost for Lemmy to launch to compare, as it has a UI a little closer to RIF's.
None of them have the ability to jump around to top comments like RIF had, but Liftoff does at least seem to want to add those features as they progress, which is another reason I'm sticking with it over Jerboa and Connect ATM.