I finally started my Titan this weekend. I got him through the story line. I got a Legendary elemental auto rifle dropped that I hadn't seen before. It's the Suros Galliard-42 I have paired it with the Titan Exotic chest Actium War Rig. This pulls ammo from your reserves if you have the AR equipped.
This gun was amazing. I actually beat the final boss using it as I couldn't figure out how to use the Striker super when Gaul is in the air.
The cool thing about the chest piece is as you're firing, it add ammo as your firing so you can fire longer.
I've been tearing up the crucible with this gun. It has decent range and with a mod to stabilize your energy weapons it's pretty darn stable. If I can put the aim on my opponents head, I usually win the encounter. But I'm still tending to shoot at their feet. I don't think there is a crit spot on their big toe.
Now, you all know that in D1 I've not been an Auto Rifle guy. I hated them in D1. I am loving them in D2. I have a couple different ones on my Hunter that I like, but this will be my goto AR on my Titan.