If you're going for something easy, pick Invective. I completed it in a couple of days, without even actively trying. The PvP portion is insanely easy, don't let the description mislead you. It'll tell you to get a 25 k/d spread in the Crucible, but they mean over a period of time, not in one game. I completed that in 3 matches, and I don't consider myself a strong PvP player. I've heard assists count as well but I can't confirm this. You will need about 12k glimmer to buy special ammo packs. However, I don't even use Invective, I actually have a better legendary shotgun for PvP. It's currently just a trophy. I'm working on Bad Juju now, still grinding out the 25 strikes, but I'm taking my time on that as well. The next section is supposed to be getting 10k points through kills/assists in the Crucible. I don't really use pulse rifles, but I'd like to collect it anyway. Thorn... Thorn took me a loooong time to beat. It was actually the first exotic bounty I took. The Crucible section was especially painful (500 point void kills, kills grant 5 points, death subtracts 2, it is possible to go back to 0), and then there's the Epic Summoning Pit. BUT, I actually like Thorn, now that I have it upgraded. I love Hand Cannons in general. Once you unlock its special upgrade, it's pretty fun. It has a DoT effect and it pierces targets. It's always cool to get two kills with one bullet. It's allegedly a monster in PvP, but I haven't practiced enough with it to say either way. Keep in mind that both Thorn and Bad Juju are supposedly getting buffed in the future. TL, DR: Invective is far and away the easiest.