Ember has no Daedric Summoning, not even temporary pets, that's kind of disappointing.https://eso-hub.com/en/companions/ember
Her Ultimate is Eye of the Storm morph from Destruction Staff rather than a class ability, filling out the rest of the Lightning Caller tree is Crystal Shard, Mage's Fury, and Lightning Splash. Her Mischievous Caster has Lightning Form, I assume Trickster's Trap is Daedric Mine, and Restraining Prison (Encase morph). Her final tree Playful Schemer uses non-sorcerer class ability with a basic direct heal, a mini-haste ability with Second Wind, and Ward Ally.
Overall she does have some nice AOE effects with Lightning Form, Lightning Splash, and her Ultimate. She may prove more useful than Mirri with Dual Wield and Shattering/Aggressive Medium Armor; I'll set up her up with Shocking Burst, Spinning Steel, Razor Cape, Hurricane Visage, and Second Wind. This would give you two kinds of cast and forget (third with her Ultimate) AOE pulse damage with damage reduction, a ranged AOE attack and a melee AOE attack followed by cooldown reduction to bring everything back up. No Masque of Torment, but her Entomb (Restraining Prison) would work sort of like that.
Isobel is a Templar, go figure. /sarcasmhttps://eso-hub.com/en/companions/isobel-veloise
Her Ultimate looks to be a Dawnbreaker variant with Sun Fire, Puncturing Strikes with Empower, and Radiant Destruction to fill out her Blazing Might tree. Brilliant Shield tree has Sun Shield without the damage component, Toppling Charge morph, and what looks like an AOE cone version of Piercing Javelin; that's actually kind of neat if you could line up enough targets. Healing Grace has a unique burst heal with secondary heal over time, Cleansing Ritual with a snare, and Purifying Light morph.
Her Ultimate may suffer the same problem as Bastian where you need to have her in melee range to make it useful, so putting on any ranged weapons that aren't Frost Staff may prove to be counter-intuitive. I'll likely set her up with Two-Handed and Quickened Medium Armor to make use of her Gallant Blitz (AOE off-balance), Holy Ground (instant snare), Penetrating Strikes (Empower bonus), Sunder, and Spear of Light (AOE Knockdown). Like Ember she too has quite a bit of AOE at her disposal AND has a gap closer that hopefully is more reliable than Mirri's Warp Strike which has a tendency to cast and do nothing.