Army composition question

[carlec]

How do you know when to get rid of a unit and move on to some other unit? I mean, at times it is easy to see that a stronger unit (say, Ancient Bears to Bears) just makes sense, but at other times, it doesn't, at least not to me.

So, right now I have both Priests and Archmages (I'm a Paladin). I can start, now to get Inquisators. Do I drop the Archmages or Priests for them? They don't seem to do the same kind of attack, so I can't really tell. Adding to the challenge is that I seem to be out of Archmages, at least for now.

I am level 11 (I think) and am just now getting to the mines. I have only done a few quests on the Islands and most armies there remain stronger than mine.

My current army is:
Bowmen (109)
Royal Snakes (7
Priests (105)
Archmages (27--but I only currently have 6 or 7)
Ancient Bears (5

I think its time to get something new, but there are no horsemen so far, only a few knights and, well, I'm just not really sure what to upgrade or move on.

Ideas?