Even though I really like this game, I found starting out a bit overwhelming, especially selecting the right units for my army.
Until I started reading up comments in discussions and other guides, I kept hiring units that were a waste since either their highest tier is rather underwhelming or simply because I hired a unit that progressed into the wrong branch on the promotion tree.

I kept thinking for myself that it would be great having a place where I can look up and compare high tier unit stats on level 20 and also see the whole promotion tree, so when I need to decide whether to hire a unit or not, I can make an informed decision and not just simply rely on the name. Unfortunately, the Sands of Salzaar wiki wasn't much of a help either. It (kind of) shows the promotion tree but no stats and skills (which yes you can look up in game, but only after you hired a unit that is somewhere on that specific promotion tree).

For this reason, I thought I compile a very simple guide, which contains the stats of the units, which I find great to use and the promotion tree as well as where to get them. I started with units that I personally really like, however, I, by no means, claim that this is a complete guide nor that any units not listed here aren't good, so I'm happy for you to comment with more great units and ideas. Since I am a newby myself, there are, most likely, a lot of great units that I missed, so I'm happy for you to let me know more great units and ideas. I myself would love to discover more amazing units or different ways of playing the game. :)
Will try to keep updating this guide with more units.

Note that I didn't discover these units on my own but rather took what other players recommended in either discussions or their own guides.

Hope this guide provides some help. :)