The Autarch, whom we know and love, benefits a lot from being properly positioned. The Path of Command ability requires careful placement of the Autarch and the units being supported to make sure the benefit is granted. Many of this weapons have a short range, and his assault ability requires good positioning as well. So, what are our options for Autarch mobility, and how do they stack up? Here I examine the 4 Autarch entries in Index: Xenos 1.
Autarch on foot:
Our default Autarch on foot has good Eldar infantry movement and Battle Focus, making for pretty decent mobility. Nothing special here, just a normal infantry unit for Eldar. If this model will be in the backlines, a Reaper Launcher might be a good choice of weapon, since it will let his shooting remain relevant even if the enemy is not close by.
The foot Autarch won't keep up with Wave Serpents or Jetbikes, but is cheap and a good leader for footdar.
Autarch with Warp Jump Generator:
Averaging about three times the speed of a foot Autarch for a small increase in cost, the WJG Autarch loses the ability to charge when using the WJG. This Autarch can still charge, but only if moving as a normal infantry unit. It's also worth noting that this model can't typically charge Flyers, because most Flyers have a rule that says "can only be charged by units with the FLY keyword" and the WJG Autarch only has the FLY keyword when using the WJG, and can't charge when using the WJG. Although this is technically faster than the Autarch with Swooping Hawk Wings, realistically this is "Swooping Hawk Wings without deep strike, skyleap, or ability to assault as easily" without much of a reliable speed advantage due to variance. Great for shooting, though, and cheap.
The Autarch with Warp Jump Generator is very fast, and a great choice for a shooty supporting Autarch.
Autarch with Swooping Hawk Wings:
The Swooping Hawk Wings are a moderate cost increase in return for a doubling of speed, permanent FLY keyword, and both Deep Strike and Skyleap. Compared to the Warp Jump Generator, Swooping Hawk Wings are slower but allow for a lot more options. You can start this Autarch in reserve and deep strike him in on turn 1, avoiding sniper shots, or coming in where he is most needed. Skyleap causes a loss of a turn or shooting (and aura) but could be useful in a pinch. Though the speed of this option is slower than a Warp Jump Generator by about 3.5" average, the constant FLY, Deep Strike, and ability to charge after fast movement (if you don't Advance) add a lot of flexibility.
The Autarch with Swooping Hawk Wings is fast, and a good choice for a shooty or assaulty Autarch, especially one in an army that will attack on two fronts, since he can start in reserve.
Autarch Skyrunner:
The Autarch Skyrunner costs 50% more than the base foot Autarch, making it a very expensive option. However, the defensive benefits (extra toughness, durability) and the guns and weapons tied to the Jetbike make it an intriguing choice. Of the Autarch options, only an Autarch Skyrunner can take a Laser Lance, which is the best Autarch melee weapon and a very solid shooting weapon. A properly equipped Autarch Skyrunner can, from 6" away, fire 4 shuriken shots from his bike, a powerful Laser Lance shot, and another ranged weapon (such as Fusion Gun, Reaper Launcher, or Death Spinner) before charging in and putting out several devastating Laser Lance melee attacks. Very dangerous.
If you want an assaulty Autarch, this is the most powerful choice. The main downside is points cost. The price tag on an Autarch Skyrunner can go north of 120 points very easily, making it an expensive HQ. Except for the survivability of +1 T and +1 W, none of this actually makes the Autarch better at being an aura-provider.
Honorable Mention: Foot Autarch inside a transport with Aspect Warriors
In theory, this should be a section of "Autarch on foot," but the way you use an Autarch that has a transport is different enough it should be discussed separately. An Autarch inside a Wave Serpent will be able to help out Aspect Warriors when they hop out, adding to their shooting, and assaulting. As he is inside the transport with them he will be able to keep up without difficulty. An Autarch with a Power Sword and Fusion Gun comes in under 100 points and would go well with any mechanized army. Of course, he won't be providing bonuses foot units that don't have rides, or their transports themselves in the first turn or so when he is inside the transport. If you don't need to apply the aura to units outside of the transport on early turns, and your Autarch will mostly stick with the mechanized unit, this is a fine (and cheap) choice. A mechanized list might still want to consider a jump pack or skyrunner Autarch to provide support for the Wave Serpents, but a transported foot Autarch works fine and won't get hit by snipers early on.
I'm working on an Autarch right now, I may try to magnetize him to either be on foot or have Swooping Hawk Wings. What's your favorite way to run an Autarch?