Another vote here for Sygate. I used ZA for a long time, but found that it was not as stable as sygate after updates. I use Sygate Pro and have never had a problem with it. ZA is easy to configure and in fairness to the product I have not used the latest and greatest, so it may now be more stable.
I am a creature of habit. I know Sygate, I liker the product and will stick with it....My two cents.