Okay, so I've played Titan exclusively since release and defender is my favourite class. Really your defender build depends on what you want to do or the role you want to play. Classic pve build uses one of the super charging exotic primaries (bad juju or zhalo) to build super fast with the purpose of using helm of saint-14 to blind enemies. Makes some encounters trivial really and has excellent utility. Alternatively you can run a variant with the glasshouse looking to keep your team buffed with armor or weapons of light. Really though my favourite pve builds centre around using no backup plans max strength and regenerating shields. I like being in Melee range so I tend to opt for an exotic shotgun in these encounters. Just remember that force barrier and blessings don't stack so run weapons or armor. If you feel like supporting the team more add in iron harvest to your build and the bolt caster to generate stupid amounts of orbs for your team. A very niche build I run from time to time aims to make you basically unkillable in pve by stacking armor. Spec for max armor including chest piece, then utilise Boolean Gemini to build +3 stacks of armor. Add in no backup plans with regen shield and max strength and you can basically just laugh in aliens faces whilst they blast you. It's complicated to keep up but very strong. I'll have a ponder on pvp builds and report back. I can only really think of a no backup plans build aimed at keeping overshield up + Monte Carlo just in case. You can go full support with the glasshouse if you want to be a team player. Alternatively mix weapons of Light with a high powered sniper to land one shot body kills and make people salty.