I'd like to offer a dissenting opinion and suggest you stay away from the Danes (or the Vikings in VI). I am by no means an expert player, and my first Danes campaign (which wasn't my first campaign by a long shot) ended with me being eaten out of house and home by the multiplicity of heirs. Now maybe coming from similar games you won't run into some of the problems I did, but I would suggest the English or Spanish. I actually played my first campaign as the Almohad on Easy, and ended up winning the campaign despite never utilizing their best unit, the Almohad Urban Militia.

I just got back into a campaign (English, my favorite faction) on hard after a hiatus from the game and I realized that my tactics need some work. If you have a background in TW games I wouldn't think you would really need to start on easy, but I don't think you'd like starting on expert either. Make sure to read some of the excellent guides/posts on here and try out different tactics on the battlefield.