Yeah, the Axer is a great light (reach threasher is a beautiful thing) in addition to having an animus that really helps out your melee threat range.
The Impaler is what you take when you want to go for a more shooty battlegroup, especially if you have a Diretroll Bomber. The farstrike animus is great for getting some real ranged threats, as otherwise most troll shooting isn't long enough to threaten backfield models. Long ranged Bomber shots can be quite nasty generally, and an extra turn of lobbing those big templates, as well as being able to threaten backfield models or the enemy caster is what makes the Impaler a decent choice.
The Diretroll Mauler or Earthborn are the two major melee heavies, and either one can open up a can of whoop ass. Earthborn has a few more tricks, Mauler generally has better damage output (Earthborn's can be a bit variable). One of those along with your battlegroup will be a good start.
For infantry, Fennblades are pretty good, especially with their U/A. Fast, hit reasonably hard, decent
DEF when charged themselves thanks to set defence. Champions are also good, but you probably want the Kriel Stone to really make them a solid block (as they do rely on thier armour a lot), and they're a bit slow in scenarios. Pyg Burrowers are another great infantry choice, a bit trickier to use, but lots of fun.
That pretty much exhausts my knowledge of trollbloods, so good luck