[PvK]

My opinions/experiences (which I have little interest in arguing with anyone about, BTW, especially if the word "useless" is going to be exaggerated):

Banes can make good thugs if you use them carefully.

A few Wights can be good accent for some careful mixes of troops.

Giant Scorpions are easy for some mages to cast and are not terribly expensive and fairly tough & dangerous.

Wyverns I have always had bad luck with, and usually would rather use air gems on many other things, but they are fliers, which can in theory be used to good effect in some cases.

Hawks are good for the fast flying leader, for attacking very weak targets/provinces, immediate attacks anywhere on the map, providing air fodder, flying hold & attack rear light strikes, etc. I usually like to summon them to a friendly province so I can script and formate them before use. I also often separate the leader from the minions. Sometimes you have flying troops with know flying leaders, so the hawk can lead them for much improved map movement (e.g. indy Pegasus Riders).

PvK