It really depends what you want...are you just looking for a discharger to quickly discharge the pack after a run or you want the ability to do cycling/heat up the pack/lower IR? If all you want is just a simple discharger then I would get the Skyrc BD250. The Hitec AD380 although has a higher discharge rate, all its other bells and whistle seems very useless. No idea about the Pro Performance RC inc Annihilator, just seems like a big resister pulling 100A. That just sounds like an disaster waiting to happen.

The SkyRC or Hitech (basically rebrand of SkyRC) cant discharge to storage voltage or run cycling programs. No idea about the Pro Performance RC one. If you want to do cycling at high discharge rates then I dont think the X5 is capable of doing that. You are better of buying a different charger like iChargers with that function and have either an external resistor or regenerative discharge where you discharge power back into a cell. \

RCdischarger is a pretty hard pill to swallow at 400+ bucks, but its a complete package which can handle high discharge rates doesnt just turn electrical energy into heat.