The main advantage of the official F-Droid client is that it’s always at least as up-to-date as the main repo-server system, so improvements propagate immediately, for years now.
The main disadvantage (imho) is the interface, so most forks improve that (per each dev’s opinion).
This itself is a disadvantage for the forks, b/c very few (if any) have enough of a dev/userbase to survive the original dev’s eventual demotivation to continue to update to match the OG client’s actual improvements.
Having gone through the client cycle of official 
fork several times, I’ve finally settled on the official fork F-Droid Basic. IMHO, the interface is still not as good as the OG’s original before the UI refresh a few years ago, but its backend is superb & regularly improving, & gets rid of all the cruft I’ll never use. Since I don’t live on the client, this is the best there currently is.
Still waiting on repo subscription import/export, though, from any client.…