"Forward, Vikings!" - in my opinion, it's not a very difficult map. I easily won it: capture 2 other castles in Scandinavia, and methodically eliminate all enemies.
I completed "Lake of Plague" by winning on the 6th month. I don't remember how difficult it was, but it doesn't seem to be the most challenging map.
I only passed "Valleys of War" on the 3rd try, and even then, I was on the verge of defeat. That was 3 years ago. The map doesn't seem difficult. Now, I might be able to handle it better: experience does help!
"Appeal" - this is where I struggled, but I won!
"Defenders of Gelia" - the closer to the end, the harder it gets.
Scenario 5 from the "Against the Odds" campaign: I replayed it just the other day - and won! But the first time (3 years ago), I lost. Now, my rich combat experience helped! :)
(Василь Симоненко. Люди – прекрасні)