Can't decide for Raul what to do in the end of his quest, does anyone know (backstory maybe?) what would make him happiest?
I prefer the repair perk but he doesn't sound too enthusiastic about it, even though he brings it up himself. Can't decide...

Well, one option has him making peace with old age and finding ways to still be helpful to people, the other embracing a new active, 'youthful again' phase of his life. This one also has him hunting down people who prey on the weak, like he did in his last story. Either of them leaves him happier than staying in the rut he's currently in and both have him find again his purpose and place in the world. I personally don't prefer any of them to the other, unlike in other companions' stories, so usually I go with whatever my current character would consider the better option. What does your character think?

They both technically make him happy. If you convince him that being old isn't so bad he will be happy for being a useful repairman. But will always miss being a gunslinger. If you make him go cowboy on the world he will be happy because he is doing what he knows best, shootin!

The only thing that would really make him sad is not knowing where he fits in the world.

Whatever you say boss...

He doesn't really care. Either decision makes him a happy 'ol ghoul.

Following my chosen dialogue options, Raul comes up with this:

"I swore I was done with the gunslining life - I was too old,
too slow, and too beat up to protect anyone anymore.
I thought I was done forever... but after traveling with you, I
realize I've always had my doubts.
About whether I'm really too old to keep living the life of a
gunslinger after all. And after seeing what you go through,
boss, I think I am.
From now on, I'll let you deal with the fighthing and stick to
keeping your gear working. I don't want to slow you down
more than I already do."

Choice 1:
If that's what you think is best, I won't stop you.

Raul's answer:
Thanks, boss. I'd hate to think I was dissapointing you with my life-altering decision.

Choice 2:
[Speech 66] That's not true, Raul, you're great with a pistol.

Raul's answer:
You think so? Wel... you're the boss. Okay, I'll give it a try.
But if I get killed, and if there's an afterlife, I'll haunt your ass.

I initially intended for him to go with the retirement/repair option, but the way
my character says it (I won't stop you) and the sarcastic way Raul responds
just makes me feel he'd rather return to his gun-slinging ways?

I need to do his quest. This is the one follower I have not done this with yet.

Make sure you do it before completing Volaire! Loyal has a tendency to disappear.

The story he tells is worth the trouble. Definitely one of the better pieces of writing in the series.