I've only played the Earls and it's reportedly the best. It was set up with the intention of hosting major tournaments, so it's long but there are some absolutely stunning holes. I got far more enjoyment playing there for £20 than playing either the brabazon or PGA at the Belfry.
There 2 very different courses, the Earls is tree lined and tight in places, but a very nice course at this time of the year, the Kings is a little more open, undulating and straw/grass mounds line the fairways and there's water to carry and navigate.
Can be slow if behind large societies or if its very busy.