I've been trying to find a sync replacement as well, but nothing can quite give me what I want from the interface. Double tap to zoom (also double tap with hold and swipe to zoom in and out would be a plus), zoom on gifs and videos, single tap (or swipe) to dismiss pic or video, and a deep limit on how far you can zoom in. Oh and swipe gestures to upvote and return to the main page.

Thunder comes closest but there's no zoom on videos.