Just to clear this up...
Clear Channel did not buy prophet systems, they ended up with Prophet Systems after Capstar/AMFM bought them prior to Clear Channel's takeover of the AMFM properties.
That said, Jacor and the Capstar properties of AMFM all pretty much used prophet.
At the time, RCS Master Control was preferred by Jacor, however, the wancast/remote voicetrack capability of Prophet made it the winner.
If I had to go the free route:
1) Rivendell---on Linux, it's free, open source and so is the OS. Linux is darn near bulletproof in it's reliability. Almost boring to own a Linux machine...no excitement like crashes and stuff.
2) Deltatrax---pretty decent stuff!
If I had unlimited cash:
1) I'd outfit my stations with NexGen, w/backup server and local workstations for full redundancy.
Prophet makes the best automation system there is, their support wins hands DOWN. I've worked with 7 or 8 different flavors of automation. Prophet tastes better.