And which ones are easier to play against? And which heroes would you use then?

I usually play as Fortress, and I don't really have any major problems with Necropolis... I think magic plays a big role for me, and it's not too difficult to defeat those skeletons, in my opinion... and archers =) Even if they are fast skeletons, they won't reach you in one turn, right? And when they do reach you, half of them are already gone, shot down along the way, and we take out the other half with nagas, enhanced by the hero's spells and djinns... For me, the situation doesn't seem that difficult...