well, Lugh and Come Together, i reappraise my opinion of the French and Turks, both are rewarding if you can get the economies and horse archers working respectively, i have very successful campaigns going on both now. Poland, on the other hand, has twice been a sad failure...! can't be bothered with Aragon, having one province to start is dull.
Sicily looks tough, but in fact is not; good heirs, lots of ships, lots of mercs available. invading north africa and using crusades can get you a huge cut-throat Mediterranean trading empire very quickly, which is just as well cos loyalty (and therefore tax rates) is often a problem, as your king is usually cut off from most of his provinces by sea! keeping him in Tunisia or 'on tour' seems to work best.
war with the Italians is inevitable though, and i really hate the unpredictability of sea battles.

following more experimenting with VI, i found Scotland to be impossible and got 'vikinged' to death immediately. the Vikings themselves are great fun, but i eventually gave up cos all the AI factions promptly allied with one another and never broke any alliances in 150 years of play. consequently it got to the point where almost any province i raided had in excess of 1500 men in it...