I don't understand why there is a comparison here. They all have a different functioning algorithm plus have different features.
CC: Caffeinated Content for WordPress: Fetch and schedule posts from Youtube (videos), Yahoo Answers and article directory (only one directory, i guess). The pros being you can schedule posts to far future from anytime in past, that is I can make my blog look abt 6 months old and schedule posts for maybe an year. The cons is no good translation and severely bugged (obsolete) plugin now. Unique feature being it can post past in time. It rocked till it was working
Autoblogged: Feed Syndication Plugin: Synonimizer support, can post feeds in a powerful manner. Allows time controlled updates etc. Works way effectively and strongly with Yahoo Pipes. The Pros can be the powerful feed fetching features it has incl. fetching feeds from various searches, but the cons being that it can not fetch keyword related articles from other sources, like yahoo answers, article directories etc.
WP Robot: Powerful fetching algorithm. Can fetch from Article Directories (2), Yahoo Asnwers, Flickr, Amazon, ClickBank, YouTube and eBay. Time controlled fetching abilities. Does not schedule but rather works on cron updates, so kinda slow. But the variety of sources, auctions and the powerful MIX feature is awesome. WP robot again can not be used for feed fetching but has an incredible built in translation module.