fable,
I am sorry to disappoint you but Rot3K XI is largely considered a flop in Japan. It seems Koei tried too much fancy staff, such as graphic (which is good) and effect, while the management system would leave you frustrated. I haven't played it, though, because the reviews were so bad I didn't want to spend so much money on it.
Among Rot3K series, IX with PK is still considered the best (with PK, mind you), while V, VI, VII were generelly kind to new player. I played VII on PSP recently, and it was enjoyable, though I spend more time on IX with PK on PC.
As for Nobunaga series, there were big debate which is the best. The newest seems to be the most interesting to me, and I will buy one next time I go home.
Oh, and my ancester is always in Nobunaga series.
