Welcome to the game.
Coming from a SC2 background, you should have an advantage by being much better prepared for unit micro. Most players here are quite allergic to the concept.
With this in mind, I would strongly recommend Aeon. While you should definitely play all of the factions a decent amount to better understand their strengths and weaknesses, many of Aeon's units are simply impossible to mass-efficiently counter when they are properly controlled. I'll do my best to share my knowledge of the game regarding the specifics you mentioned:
I like early agression.
UEF T1 looks appealing, but so do Mantis
UEF has a very solid all-around land force, with their only deficiency being a lack of hover units at T1, and no hovering shields are flak at T2. Their T1 tank, the Striker, is perhaps the quintessential tank - no real strengths or weaknesses. Their T1 mobile artillery fires a bursty, very high damage projectile that is relatively slow. However, their Light Assault Bot is easily the best of the three that have one, and scales well with micro.
Aeon has the best land force at T1, without question, due to the way their tanks work. The Aurora has less HP than other tanks, but more range and far more maneuverability. Try out it's micro in sandbox and get used to how it's controlled; at a high level, you simply move back when the enemy advances, and forward when the enemy retreats. If you get in range of other tanks, quickly move side to side to dodge projectiles.
Cybran's land is rather weak at all levels; every other faction simply has something better. The mantis' biggest advantage is that they are harder to outmicro due to their higher ROF, but this is very rarely an advantage since most players simply do not bother with unit control at this level.
Seraphim is very strong, but their advantage relies more in the fact that their units require very little control and instead force others to micro. They have no LAB at T1; their tank is similar to UEF's but is more frontloaded, and their artillery is the best of all with very high damage and the ability to hover.
I like a strong airforce (not necessarily early-game)
Each faction's air is roughly equal, with again the exception of Aeon's. Aeon is the only faction to have T2 interceptors, which, with micro, cannot be mass-effectively countered until T3. Combined with being one of the only two factions that have two levels of RAS upgrades on the ACU (the other being Seraphim), it's easy to see why Aeon is generally the faction of choice for air players.
I like drops
If drops are a favorite tactic, I would recommend Seraphim for their artillery, and because their transports have more slots for units than other factions'. UEF and Aeon arty are both decent, while Cybran's is fairly weak; it's inaccuracy makes it a poor choice for taking on structures, combined with its cost.
I like a mobile style of play
This is one constant among every faction - map control is far more efficient than turtling, so every faction is forced to play offensively and move quickly.
I do not like proxy bases
'Attack of the Bases' is not my thing
In 1v1s, it's generally impossible to efficiently PD creep as there are simply too many cost-efficient counters to it. Smash them with mobile artillery, TML or MMLs.
- in fact, I might need a little bit of micro or else I might get bored. 
and they get a t1 gunship too. Beware though, atm their arty is sucky...
