Svirfneblin Gunslinger build suggestions

[Ellsworth]

We are starting a new Pathfinder 1e campaign. I have read many of the gunslinger posts on here. I have chosen to go with 20 levels of gunslinger, I have not completely decided on the archetype but I am leaning towards musket master or pistolero. I'm working on a competent build but it doesn't need to be completely optimized. I have optimized in the past and want to change things up a little.

One Homebrew rule we have the option of using, we can select one first level class ability from any class.

Race: svirfneblin
Str 8
Dex 18
Con 11
Int 12
Wis 16
Cha 4
Speed 20

I would be interested in getting some suggestions for a first level class ability to take. There are many to choose from and I'm having a hard time deciding which one would Grant the most long-term benefit. On the short list already is the Monk ability to add wisdom to AC or fast movement from barbarian.

We are primarily using most Pazio books with some minimal 3p content.

Thanks for the advice.

[Kurald Galain]

The gunslinger is a bit of a one-sided class, so for the other ability I'd pick anything activated (not a passive bonus) so to give you more options in combat.

For instance, the oracle's Misfortune ability, the arcanist's Dimensional Steps, or the mesmerist's Vanishing Stare. Or just get a familiar...

[skypse]

Is the ability going to level up with your main class?

If yes, you could also consider rage or eidolon. If archetypes are included, you could get the Ubran Barbie archetype for free Dex bonus.

[Ellsworth]

Is the ability going to level up with your main class?

If yes, you could also consider rage or eidolon. If archetypes are included, you could get the Ubran Barbie archetype for free Dex bonus.

It is not going to level up. It will always be level one.

Archetype are included.