I've been looking at some song presentation software to use at different events and I decided to invest in ProPresenter by Renewed Vision. I like it because it's focused on song presentation and doing that one thing very well. Some of the other programs I tried seemed to be trying to do too much and as a result, don't do any one thing well.
The other reason is stability. ProPresenter just seemed to be rock solid whereas some of the other ones crashed on me when I tried to push them. That is my anecdotal evidence, not the final word.
But I'm very happy with it, particularly being able to tie slide timings along with an audio track and the way it just smoothly handles video. I found it easy to use even though the help files were quite short. I never got comfortable with some of the other options.
But ProPresenter is Mac only. And for good reason. It's easy to support. Apple inserts some of the best tools for visual presentations. Macs have supported multiple monitors for years (compared to the problems that Windows has suffered with video drivers for a single monitor) and has the most experience with video playback. It also seamlessly integrates with the iLife programs so you can drag and drop in pictures, movies, and audio clips from QuickTime, iTunes, and iPhoto.
And if your church is growing in complexity is using media in services, you might find that switching to the Mac platform, while initially requires work, will turn out to be a great thing. You can do a lot of the same things on a PC but the workflow will likely be more cumbersome. And when the heat is on in the middle of a service when a change needs to be made, that can mean all the difference between something that goes off smoothly and something that becomes a distraction.