I am an avid carp angler, and use many different baits. None are more effective than corn. Another highly effective hook bait is the tiger nut. Unfortunately these are usually found at carp specific outlets. There are a handful in the US, that can be found with a simple internet search. You can find them prepared or dehydrated, which will require a bit of cooking. The benefit of cooking your own is that you can flavor them to your liking. As far as pack bait, classic oats pack is highly effective. It is simply 1 tub or old fashioned oats, 1 can of cream corn, and then any combination of powder jello, breadcrumbs, flavorings, or anything else you can possibly think of. An important note on pack baits is to test them in the margins for breakdown times. A pack ball should "let go" inside of 3 minutes for maximum effectiveness. One of my favorite aspects of carp angling is that you can stop at any convenient or grocery store and load up with many options for bait.