Welcome news for those of us who like Fbreader: it can now sync your reading position via Google Drive and a new service called "Fbreader Book Network". This is now built into Fbreader, not a separate app like FBSync. See
Google Play here and
Fbreader Book Network here.
I like the sync because it is automatic (as long as you have data or wifi connected). Moon+ lets you know that a new reading position is available and asks if you want to go to that position. Fbreader's new sync is more like Google Play's: automatic with no prompting.