Holland makes a great trading nation.I've already done an England game, which was incredibly easy
Ottomans are too much work, with all the wars they start with, it's crazy.
Though the Golden Horde looks nice for a future, war aimed game (except for every time your leader dies, it's like a total civil war).
Instead of Portugal, I think I might try a lowlands country (much smaller, but isn't too hard to cope with).