Who do you favor to tag along when doing mission in dwemer ruins?

I first took Mjoll the Lioness from Riften to the Alftand/Blackreach mission for the main quest. I thought that her experience in dwemer ruins such as Mzinchaleft would help. I was wrong. All she kept constantly bragging about was her adventures with her dad all around Tamriel as I looked for the crimison nirnroots for hours.

I read somewhere that a sellsword in Markarth named Vorstag has extensive knowledge and fascination with Dwemer ruins. Should I hire him?

the pet dwarven sphere you can get on solstheim

Though its easy to mistake for an enemy...

I would take J'zargo and put him in Light Armor. Although you need to complete his missions for him to become a follower..

If you don't wanna do that, then try and get your Conjuration to 50 and summon a Frost Atronach along with a mercenary.

If you're not really a mage, then head to one of the court wizards and buy the 'Conjure Familiar' spell and spam it on your enemies.

I personally tackle Dwemer ruins alone because I love the feeling of it just being you, the lifeless ruins, and the constant sound of moving gears, cogs, and contraptions.

Katria was a great temporary companion for the Dwemer/Aetherium quest, even though she was a ghost..

I have lvl 70 conjuration and I don't even know how it got that high. As you said, I'm not really a mage and i rarely use anything but enchanting or restoration.