I've been feeling really good about my Deep Gnome Wizard, an Illusion specialist. My main attack is two Phantasmal Killer innate-spells (so they're cheap to cast) with a DC of 65.

For generic attack I have Improved Shadowblade ranged which also knocks down SR by 9, though I seldom need it for that. It has a Draconic Destiny Mantle rider so it does a bunch of extra fire damage with four ticks. That's also an innate so cheap.

Mass damage I have Meteor Swarm (fire + force) and Arcane Tempest (force). Not innate so kind of expensive and I try not to use them.

Crowd control I have Greater Color Spray (innate illusion), Otto's Irresistible Dance (one target but no saves, I use this against Reapers as a backup to Greater Color Spray), and Otto's Sphere of Dancing (not that great a DC but it's a lasting area effect so you can run bad guys in and out until they fail).

All the above are my main toolbar, along with Arcane Insight (+6 DC and SR for 30s) and Master Illusionist (everyone in party has 95% concealment for 15s).

For undead work I replace Sphere of Dancing with Halt Undead. It's not that effective and it centers on where the target was at the start of casting so if I'm being chased it often misses. Much better with a second party member make the undead stop at a spot. Otherwise against undead I have to go heavy with Meteor Swarm and maybe Arcane Tempest if it's an undead that stays still. Sometimes I can snipe with Shadowblade.

For constructs it's also Meteor Swarm and maybe Arcane Tempest. Against things that heal with fire then I have to turn off my Draconic Mantle and rely on Shadowblade which is a hard row to hoe. Luckily construct people and dogs Phantasmal Killer works fine. It's things like mechanical golems and floating drones that suck.

In both cases I keep Greater Color Spray and Irresistible Dance because those are mostly for anti-Reaper work.