One of my favorite gamemodes, outside of Conquest, is Assault. Hi-Rez's take on the popular ARAM mode featured in most MOBAs, Assault features a single lane with 2 towers and a phoenix before the enemy titan. Assault prioritizes strong waveclear, burst potential, crowd-control, and sustain. Many gods perform well in assault, but a few stand out as top picks. My favorites are listed below, in no particular order.

Agni
One of the oldest mids in-game, Agni excels in a number of areas. Agni can easily stun the majority of the enemy team with a well-placed 'Noxious Fumes/Rain Fire' combo and follow-up with relatively high burst. As far as mages go, Agni also has an excellent disengage with 'Path of Flames', which is vital as the tides of battle turn quickly in assault. Lastly, 'Rain Fire' manaless casting cost means Agni can freely harass the enemy team without sacrificing waveclear.

Ares
Ares is a fantastic support god in assault. In a game mode where aura items are invaluable, Ares benefits from buying as many as possible. With limited options for active items, since Salvation is almost a compulsory purchase, Ares will most likely catch one unaware person with 'No Escape', usually resulting a kill. The highest damage output among guardians, Ares can also provide much needed magic damage if your team could not get a mage. Lastly, the combined cripple/slow on 'Shackles' is irreplaceable in Assault, where low mobility usually means a quick death.

Praise be our lord and savior Meditation.

Artemis
Artemis is my favorite hunter in assault. Great teamfight potential with 'Calydonian Boar' and harass using 'Suppress the Insolent,' Artemis brings a lot to the table. As a true lategame carry Artemis also benefits from the increased gold-spooling getting key items like Deathbringer, Qin's Sais or Titan's Bane earlier. Secondly, Artemis' 'Vengeful Assault' allows her to swiftly tear through enemy defenses. In a gamemode where objective play is key, having an early advantage can be the deciding factor.

Bastet
High burst damage with the 'Pounce/Razor whip' combo, factoring in the additional 15% damage using 'Open Wounds', Bastet's high mobility and aggressive playstyle fits most team comps. A strong counters to most mages using 'Cat Call' to harass and zone enemies. 'Cat Call' also transitions well into the lategame to tank objectives and secure the win. Bastet's major weakness is a small mana pool which can hinder her early game.

Geb
Great initiation potential with blink into 'Cataclysm' leaves the enemy team vulnerable to follow-up burst. The knock-up on 'Shock Wave' excels at holding enemies in place but is a weak enough form of crowd-control that most enemies won't use 'Purification Beads. With 'Stone Shield' saving allies and infuriating enemies, Geb less aggressive play style, compared to an say a Sobek or Athena, means a great counter-initiate once big cooldowns are used.

Hun Batz
High mobility using 'Somersault' and 'Sacred Monkey', Hun Batz can quickly reposition himself, excelling at initiation and disengage. Similar to Ares, Hun Batz dictates enemy players purchase 'Purification Beads' or find themselves scattered under the effects of 'Fear No Evil'. The lasting fear leaves enemies open to follow-up damage and the dispersal effect means an effective counter-engage can be difficult to coordinate. Lastly, Hun Batz' early game damage can be surprisingly high when you factor in the extra damage from 'Infused Strikes.'

Mercury
Mercury's role as a hyper carry is especially evident in Assault. Tearing through enemy structures with 'Maximum Velocity' and great harassment using 'Made You Look' makes Mercury one of the best assassin to roll. With a well-coordinated team, Mercury has great pick potential using 'Special Delivery.' Mercury also excels in teamfight scenarios with a team wide disorient off of 'Sonic Boom.' Lastly. Mercury can use his ult to quickly traverse the lane and backdoor the enemy Titan with ease.

Ra
In my opinion, Ra is the best healer overall, narrowly beating out Hel. With equilivalent magic power Ra's 'Solar Blessing' heals for nearly double the amount of Hel's 'Inspire'. However, 'Solar Blessing' has double the cooldown as well and requires 6 seconds on immobility, wheres 'Inspire' heals in burst. The reason I prefer Ra is that healing and sustaining your team does not hinder your damage output. Strong harass and clear potential using 'Celestial Beam' from a distance is preferable to exposing yourself to use Hel's 'Repulse.'

Anyone who doesn't think Ra is the best healer hates freedom.

Zeus
Zeus' high burst damage and easy to land harass makes him a strong pick-up overall. A direct counter to several gods that rely on summons, such as 'Inferno Cannon'. An ill-placed summon will deliver a free 'Chain Lightning/Detonate' combo to the enemy team. Zeus' main counter in conquest are high mobility assassins, but by sticking with your tanky allies, enemy burst damage can be easily interrupted and set-up a counter-kill. Zeus' other main weakness, mediocre waveclear, is less problematic as Zeus can rely on allied ADCs or mages to assist him.

Unfortunately, the very nature of Assault means no one god can single-handedly decide the game. The areas these gods excel at, strong waveclear, burst potential, crowd-control, and sustain, while helpful might mean nothing if the enemy team get a well-timed deicide.