I did a poll and nearly 30% of the people who voted said they used Sync! It's stayed around that percent the whole time too!
EDIT: Here is the poll I forgot to put this here like five times lol https://strawpoll.com/wby5A21R1yA
I mostly use Sync but keep Jerboa installed and every so often play with it as well. They are very similar, but Sync feels more fluent and polished, Jerboa has this "Android 2.1" feel to it