[atlatea]

I'd recomend using all same race unit than all archer unit if you prefer for non boring and very challenging unit.

Trust me, i've tried many combinations for many walkthroughs, all ranged or mostly ranged will bore you, same with 3 dragons army, though for 3 dragons army, the boredom comes from their overpoweredness.

Use all same race unit, i mean all humans, or all elves, all goblin, etc.

As for most versatile and non bored, i'd recomend elves or demons.

I've recently finished all elves. It is fun, especially for impossible no loss game, i'm trying to do impossible no loss game 7 days run, but fail at the 7 days goal. Nevertheless, it was the best of all my walkthroughs so far.

As for elves, i use dryads (mass disabler, very strong summon, best in long battles, has good opening), elves, faun (disabler, fear and sleep is nice, can do a combo with dryad sleep, has good opening), ancient ent (main tank and main melee disabler using entangle), paladin in specific situation (usually againts geyser maniac), unicorn (for againts undead and demon), druids (best elven rage gatherer, good summoner, beast/animal disabler).