WELL WELL WELL. What do we have here? Besides Spicy doing his normal PUP bashing. (pay him no mind; he had a bad childhood experience with dolls and clowns.)
Anyhow, what you sub depends on your level. From like 1-10, I did /war. 10-24 or so I did /dnc for the drain samba, the switched to /nin for the shadows. Then back to /dnc at 30 when I had curing waltz. Afterwards, you're mostly going to be subbing /dnc solo. And using WHM or RDM frame solo. (You can worry about skilling up the RNG/WAR automatons during your free time when you can tank the mobs with only Waltz curing you.)
I suggest at level 10, get the red mage frame. It enfeebs/heals just like the base frame, but it also has more HP and can nuke too should you prompt it to. (pop an ice maneuver without damage gauge attachments on.) Then 20/30 it doesn't matter which you get. 40 is the level where you can get WHM or BLM; get WHM.
Helpful hint about WHM; if you have a status effect that it can remove with -na on and it has the skill level for that spell, it's going to -na you over cure. So if you have Healing Waltz (70+/dnc35) and need a cure but have something stupid like poison on, try to waltz it off before Automaton poisonas ya. Or, it you're lower than that, let it -na you and Deactivate it (with full HP). This will reset the activate timer and MP so you will have a fresh automaton. Activate, pop a Light Manever, and deploy. Should have your cure then.
If you need any other things explained, leave me a note or post here!
Oh, and here's the wiki page on the automaton. You can find the attachments and the spells/weapon skills it gets on there. Can also read up on the attachments for their effects and such.
http://wiki.ffxiclopedia.org/wiki/Automaton