Hello Again
Some people may disagree slightly (as I think Unbound can actually run "real" DNS zones to a certain extent);
However, I tend to stick to the following -
Unbound - DNS resolver - use in most normal cases
Bind - DNS server - use if you actually need to run authoritative DNS zones (i.e. this server is listed in NS records for some domains)
If you're not actually running any forward or reverse DNS zones on the server, I see no point in putting Bind on it.
Yes, Bind can be used as just a resolver but is a bit of an overkill, especially compared to the much more lightweight and efficient Unbound.
Yes, Unbound can be used to run DNS zones, but I think that's a bit of an "it's easy enough to add and might come in useful" afterthought.
This is exactly why Bind is gone from FreeBSD 10 and Unbound is in. 99.9% of the time people are not running DNS zones on their server, and don't need honking great Bind running. For a caching resolver Unbound is a better choice. (And even for people who want Bind, they are actually better off using a standalone package that will be newer, and easier to update, than have it built in)