The following report compares gadgets using the SERCount Rating (base on the result count from the search engine). Note: due to some search engine quota, not all result is available yet.
If working with Digital Audio and Video is your thing, then Soundtrack is a must buy. Unlike GarageBand (Which works with digital audio clips just like SoundTrack), this is geared toward the professional. It comes with a track just for video which allows you to sync up your audio with what's happening on the screen easily. It also comes with 4000 loops as compared to GBs 1000. You can get GBs accompanying software, Jam Pack, but that still offers much fewer loops than Soundtrack alone. Built in effects to each track also far surpases GBs effects. Pan your volume left and right with just a few clicks to name one. I enjoy GB and have written tunes based on it (Check macidol.com artist name Guy Serle) and it's fun. But when you're ready to do more, get Soundtrack.