With the changes made to aspect warriors in the codex, some of the abilities only work if the entire squad has the rule. This means that the Autarch would actually create problems if you tried to include them in those units.

Dire Avengers, Banshees and Scorpions all have rules that would actually cease to work if an Autarch was included. I also don’t see any real added advantage to including an Autarch anyway.

Fire Dragons, Swooping Hawks, Warp Spiders, Shining Spears and Dark Reapers all have rules that the Autarch doesn’t interfere with. With Swooping Hawks and Warp Spiders, the Autarch can actually avail of the movement rules the units have (but not the vector strike style attack hawks have).

If I were going to include an Autarch in any of these units, it would have to be one of the Fast Attack options.

My favourite way to run an Autarch, is to mount them on a bike and attach them to a small Windrider unit. This makes the unit Ld 10 and can even be fearless with a certain relic.

A Banshee mask can make the Autarch and attached unit immune to Overwatch. This is really useful for a unit like Shining Spears. The Exarchs in Warps Spiders and Swooping Hawks also have the option to take power weapons for close combat. Adding in an Autarch would give these units some extra close combat hitting power. You could also add a weapon like a Fusion gun on the Autarch to provide some anti-tank firepower. I find that both these units can be useful for popping vehicles. Hawks can land precisely where they want when they Deepstrike. This means you can get rear shots on vehicles. Having an Exarch with a Hawks Talon, gives you three Str 5 shots at rear armour (which is usually 10). In addition to that you can throw a Haywire grenade. Adding an Autarch with a fusion gun or Deathspinner gives some extra hitting power.

Although a little more risk is involved, you can try the same with Warp Spiders.