Insurance is pretty competitive, along with viagra, general adult, plus anything that has to do with money (home loans, credit cards, etc.).
Why didn't you consider Web Hosting? for a word [web hosting] to be 7-8 with CTR 2,79% I paid $5,40 Per click! Does it sounds competetive for you? Also consider how many Hosting companies are out there.
It used to be and still may be 'Mortgages'. Maybe thats why we're seeing so many foreclosures lately!
I haven't had experience with all of those PPC keywords. From my experience, real estate and internet marketing were the most competitive pay per click niches.