I thought ports were more up to date than the pkg?
(1) Not necessarily (at least by much), and (2) does it really matter? The Transmission packages are at 2.94, so they're current in any event. If you have to update all your software to the latest version as soon as it's released, you need to be building straight from the source without using either ports or packages. If a delay of a few days is acceptable, the package will usually get updated pretty quickly as well.
Now, if you need to compile something with non-standard options, you'll need to use ports. Some software doesn't get built as packages, so that would be another obvious case. And some people just have a thing for wanting to build everything from source themselves. Any of those would be cases that would call for using ports. But most of the time, if the package is available, the simplest and best answer is to use it.
Edit: I'm probably getting a little snippy here, which I don't really mean to, but some folks here just seem obsessive about updating software, and I don't understand it. "OMG the Plex package is two days out of date!", for example. Yes, it's a best practice to keep your software up-to-date, but a delay of a few days (or even weeks) isn't going to hurt anything in most cases.