With those stats, I'd say something caster-focused, but that might clash with the Oracle (though there are plenty melee Oracles viable). Preferably something with armour. Clerics are great, and with those mental stats, Shaman might be ideal. Summoners and Druids don't care much about their own stats and let their pets fight for them. Bard would also be a great idea, though maybe a bit weak in AC.
You know what would be a hilarious high-mental-stats Gnome... would be an Evangelist Cleric 4/ Medium 1/ Dawnflower Anchorite with Flagbearer and Banner of the Ancient Kings. You can stack so many damage bonuses (many of which apply to your allies as well) that even with your weak physical stats and small size, you can be a terrifying champion of holy power that super-charges the damage of the whole party. Guided Hand optional.
By level 11, you can be running a combination of Dervish Dance, Champion Spirit (+3), Flagbearer (+2), Divine Favor (+4), Inspire Courage (+3+1d6sonic), and Solar Invocation (+2+1d6fire, vs. evil); with Quicken Spell, it's all running within one round (Quickened Divine Favor swift, Inspire Courage move, Solar Invocation standard). The whole party gets almost as much as you do in added damage.
For bonus points, worship Desna, take her Divine Fighting Technique (requiring you be Chaotic Good) and get Charisma to damage and attack with starknives.
Yes, really.
I forget what the name of it is in Golarion, but it's listed as Way of the Shooting Star on the d20PFSRD, here.
A lore shaman with the arcane enlightenment hex. For once there'll be someone with the stats to make good use of it. Desna's divine fighting technique (named Desna's Shooting Star BTW) is a good idea too.
A Negative Channel Cleric. Start with Selective Channel and Neutral deity, then grab Versatile Channel at 3.
Ohh channeled smite and guided hand! Wisdom to hit and channel negative energy for the damages