I've hard good luck with omnios+napp-it. The prebuilt image is great and ad integration just works. I've used freenas, nas4free and a few other ZFS solution, but napp-it is the best overall IMHO.
I prefer the interface of napp-it because it's more manual. That being said, it is also more organized and has little hints everywhere. Many of the config pages have basic config guides right on them; it is nice.
Comstar (iSCSI, Fiber Channel & FCoE software on Solaris) is also superior than the Linux/bsd based alternatives. Comstar handles reads/writes more efficiently with less latency (personal experience only) and also seems to handle a sLog better. Switching from freenas, I saw much lower latency writing to the slog on solaris. Comstar is also super easy to set up on napp-it, all GUI based
CIFS/NFS shares are also easy to set up. Make a filesystem, hit the button to share and select users. Easy as pie. All on 2 pages as a matter of fact. Create your filesystem, hit OK. The next page that comes up is where you can adjust the shares. Again, napp-it is just organized and laid out to flow from one task to the next.
IMHO solaris based ZFS solutions are more refined and stable then their Linux/FreeBSD counterparts.