I use a bunch of followers. Sometimes I'll form a big RPG party of like 5+ of them and then spawn huge encounters of enemies for crazy large-scale battles.
My absolute favorite though is my own mage character. I played her up to level 50 or so after getting bored of my original character, but after I went back to my first character I figured out how to make her into a follower.
She's basically the perfect compliment to a melee character. She uses a combination of thunderbolt, a custom sunfire projectile spell I made that deals slightly less base damage than thunderbolt but also deals extra burning sun damage over 10 seconds (bonus damage vs. undead), paralyze, and a frost spray spell to slow enemies down if they get close. She has like over 1200 magicka but only 250 health and -100% magic resist (like Altmer have had in all other games except Skyrim), so she goes down very quickly if enemies can actually reach her. She can use wards to protect against magic though.
Custom mage armor: Ehlnoflesh (uses the Sovngarde effect)
The last big thing I figured out how to do was give her the ability to enchant sunhallowed arrows for Auriel's Bow. This is really cool because it means I don't have to constantly be going back to the Temple of Auri-El to get more and can make it rain with sunstorms all day long. She's basically the counterpart to Serana with the opposite type of arrows. Replaying the Dawnguard main quest it actually fit almost perfectly with the 3 Elder Scrolls. I used some equip console commands and suddenly had 3 scroll-bearers. DRAGON/SUN/BLOOD, each character representing one element.
