I'm not really good at telling exciting stories. The best things I did was probably saving the day on Nightfalls/Raids with a well placed Bubble a bunch of times, or vaporizing a literal dozen of mobs with on Titan Smash. Not to say that isn't fun, it's just that I draw my fun not from doing fancy stunts, but from playing to the best of my ability and being a help to my team.

But whatever, have some builds. Wall of Text incoming, brace yourself. (You seem like a seasoned player, so I'm assuming you know a bit about the class and their gear. If not, check the class perks in the build links, and the exotics here(for some dumb reason I can't filter for Titan exotics, so just ignore the Hunter/Warlock stuff).)

Defender is (obviously) a supportive class, protecting and buffing their team and generating Orbs of Light. Playing solo they can be exceedingly tanky and survive hits that would kill any other class.
Build. Explanations/Discussion on the perks I picked:

• Magnetic grenade. Personal preference mostly. I'm good with sticky grenades and like the high single-target damage they have. I just dislike all AoE grenades, so no Spike grenade. Suppressor grenades have a notable use in shutting down some annoying enemies' abilities, but deal low damage. They are useful, but a bit situational. Really try out all three and use whichever you like best.
• Catapult. Again mostly personal preference. I feel there's less difference between these than on other classes. Again try out all three and pick what feels best for you.
• Blessings of Light. If I had to pick one it would be this, but I really use all three, depending on the situation: Stuff likely to get into your Bubble? -Armor. You're likely to have a good shot at the enemy without too much return fire? -Weapons. Blessings is a middle ground, as it has both defensive use by giving a shield, but can also be used offensively, by utilizing the shield as a means to saok up heavy return fire while nuking a target. Just a few hours back, someone made a post about this, and concluded that Blessings is likely to allow for more actual DpS, here.
• Gift of Light. Because who doesn't like punching things and at the same time creating Orbs for your team? (As a side note, this makes the "create 50 Orbs" Eris bounty ridiculously easy. Just run around on patrol or something and punch all the things.) Unbreakable is good, but I feel the support GoL grants is more valuable to a team. War Machine is useful too, but to me feels a bit oxymoronic, first requiring a melee kill, then buffing your weapons. (I heard somewhere that it combines with Cascade for hilarious effects though). Really all of the options are good, but Gift of Light is the best.
• Titan Codices II and IV. All the armor one can get. Plus a bit of Agility, because otherwise I feel slow as molasses. If you value Recovery more, feel free to use TC I and/or V instead.
• Bastion. Because the longer duration on the Bubble is pretty significant. Relentless only buffs yourself, but we're a support class right now. Gift of the Void is very useful too, but for an overall support build I feel the extended duration is more valuable.
• Illuminated. Again we're support, so we our buffs as strong as possible. If you're running Armor of Light feel free to switch that one out. Untouchable is useful, but simply outclassed. Also I don't know exactly how much it reduces the cd time by. Iron Harvest is useful too, esp when combined with some particular weapons/armor (Thunderlord/Ruin Wings), but for a general support build still loses out.

Playstyle on this one is being mid range, killing stuff with weapons and grenades, and when it comes up, strategically placing the Ward of Dawn to support the team. Make sure to communicate if possible and call out the buff and where you are (and not just "here", but either with your gamertag or postion "in the corner" "right side", etc.) The "strategical" placement is something that can't really be explained, it just has to be learned by oneself. Both from experience and from observing other Titans.
As for gear, most of the exotics are good, but the order for Defender- and non-specific armor is about so: Saint-14 > Glasshouse > Ruin Wings > Armamentarium > Alpha Lupi > No Backup Plans. Obviously the "best" choice depends on the given situation and what you have available. Weapons are no big deal one way or another on this class. Use whatever you like and work best with. On a side note, Xur is selling the Helmet of Saint-14 for another 20 or so hours, GO BUY IT!

Now obviously there's some other builds I'll talk about, but a bit more briefly.

Orb-machine build. As the name suggest, this one aims to create as much Orbs of Lights as possible for your team. Changes from the original build: * Gift of the Void: Orbs at any cost. If an enemy attacks your Bubble, 3 extra Orbs will be generated. * Iron Harvest: Again: All the Orbs.

Playstyle: As above. Use Super whenever possible, and place it into enemies' line of fire. Use Heavy often, a HMG is better suited here. Kill trash with it. If you have the chance, charge a group of trash/weakened enemies and melee them all to death for more Orbs. The best exotics for this are the Crest of Alpha Lupi for, guess what, more Orbs off your super, and the Ruin Wings to improve Iron Harvest. Combine with a high-Impact MG(Thunderlord, Jolder's Hammer, Against All Odds, Deviant Gravity-A) to two-shot trash mobs.

And another build, this one particularly punchy and suited for melee heavy play. A bit less support and more one-man-tank. Changes:

• Armor of Light: Melee build, so you're gonna have enemies right in your face. AoL can be life saving there.
• Unbreakable: You'll be having Force Barrier up as much as possible, so it'd be nice if it survives for the full duration. If you want to use Shotguns over melee, feel free to go with War Machine.
• Relentless: Again, Force Barrier should be as strong as possible.
• Titan Codex VI: As a melee build you're gonna want some more speed, so some Armor is sacrificed for Agility.
• Untouchable: We're using Armor, so Illuminated has no effect, and utilizing Heavy kinda defeats the point of running a melee build. Esp as the Orbs are generated on you, so they my be out of the team's reach until the fight is over anyway.

Playstyle: Melee heavy (duh). Run in, punch the first thing you see to get Force Barrier up, then continue punching/shotgunning all the stuff. When FB drops, if you're able to, continue, otherwise fall back a bit, or use your super if you have it. As for gear: Saint-14 makes your Bubble incredibly potent, you're gonna be nigh untouchable in it (do keep in mind that an enemy's melee attack/animation will finish even if they enter a blinding Bubble with it. This means one attack may still hit you, and on Lightswitch or against a full group may well kill you.) Alternately the No Backup Plans shine on this build. They do stack with Relentless, so with a high enough STR, you can be protected 90% of the time. Ruin Wings and Armamentarium are solid choices as well; Glasshouse and Alpha Lupi not so much in this case.

Boy, that was a load of typing. I'll just leave this here and follow up with Striker a little bit later.