Gu/Ra - standard build, focuses on high damage to weakpoints, able to sub weak bullet. Lower than normal damage for distance + nonweakpoint hits though since that's where primarily all the bonuses come from

Gu/Hu - fury stance + massive hunter + automate halfline for good unconditional average damage and crazy good survivability, lowest burst damage though

Gu/Br - weaker version of Gu/Ra but has the option to switch between average and weak stances

Gu/Fi - stances give better bonuses than Hu but are conditional (front/back), other bonuses here or there like pp slayer and half/deadline (but these don't play nice with perfect keeper), I personally like this build since my average damage is highest here but burst definitely loses to ranger

Would post builds but post count to low to post links...