You should never use WTF unless you get the variant that grants immunity to electrocution. That one is an effing beast. In the first couple of modes. In UVHM, the IEDs just dont do nearly enough damage to waste any time with.
I saw the Flakker as being the worse legendary ever.. but since picking up my second Invader in UVHM, I may have to change my answer here... This sniper rifle is just... horrible. I got a lv61 one with perfect parts the first time I killed Saturn and it took me like 3 bursts to kill a slagged gun loader. I know Axton isn't the greatest with snipers but come on.
Then I get yet another invader, slag this time, from the Ultimate Badass Loader that comes out of the door before the midget room. I figured since I was playing on Zer0 this time, maybe he'll put it to a bit better use. Good god, was I wrong.
I probably couldn't even finish My First Gun with this piece of s***.
The Flakker is like a joke between my freinds and I. Whenever we do trades/dupes, we gift out a Flakker, lol. I don't know what it is about the warrier but he loved dropping it for me in true vault hunter mode. It'd be like yay! First time beating him in tvhm! High chance of a legendary! Yay!!! Congrats. Here's another Flakker. WHAT?!! NOOOOOOO!!!!! lol
Flakker I get so often that it has to be #1. Every time I see that thing I just throw it into lava and then jump in after it.
Of course I always have a copy of the Moonshot save so it doesn't matter anyways as I can farm it forever wtihout losing the Moonshot. Never saw Warrior drop any Lwgendries other than the mask (JAck mask actually pisses me off when I get it as an orange...wtf?), Flakker, CC, Impaler, or Volcano either in about 100 runs. I know those are HIS drops, but I figured I might actually see something else once.
If you like Terraria and can't wait for Starbound check out Darkout too (Greenlight it!): http://steamcommunity.com/sharedfiles/filedetails/?id=98158224