England, France or Castille in the 1492 start is my suggestion. The political situation in 1492 is more stable than in 1444, and you can get right on with colonizing if you want instead of waiting for technology to allow it.
Was England's king that bad at the start?
France at a later start date (post annexation of the vassals).
Portugal is best to start with I think. Hardly any wars against you unless you start them. Just ally Castille/Spain instead of England so you dont get dragged in to war with France. With Portugal you are in the front row seat to experience trade, colonisation and holy war fun.
To be honest the way I learned to play the game is through cheating with the console for more cash so if everything went wrong it could easily be solved. After one campaign like this with I believe burgundy I knew most tricks and had no troubles playing the game fair.