Well getting to the Ender Dragon is much harder because you have to find the fortress whereas getting the Wither is a lot easier. When it comes to the actual combat of the two, I would have to say the Wither is much harder with his constant ability to heal whereas with the Ender Dragon, you can stop him from healing.
I fight withers a lot in survival, so to me the Ender Dragon is the real challenge. The trick to making fighting a wither easy, is make sure you spawn it in a small area made of obsidian so it can't fly away and destroy everything. Then you just repeatedly hit it until it dies. It makes it a LOT easier, trust me. With the Ender Dragon, you don't really have control on the conditions you fight it in. You gotta take down all it's healing beacons, and then hope it doesn't knock you off the tower if you decided to climb to get them. The Ender Dragon is harder to defeat because you have to bring a lot of arrows because it's hard to hit it with a sword. And unless you want to get attacked by endermen, you better bring a pumpkin head and reduce the visibility by a lot, as if the dragon wasn't hard enough to see already. So there you have it, The ender dragon is meant to be a lot harder because it's the final boss in the game. case closed.
Are we basing this off of the pre-1.9 ender dragon fight? There's some pretty major changes to the Dragon fight in this next update that would definitely make it harder to kill than the wither. Hell, by trapping them in a box, me and 3 friends managed to slaughter 50 withers at once. Try that with the dragon xD
The Dragon. Nessie is definetily harder because she you can't control her. She flies through blocks & erases everything but obsidian & end stone. Not to mention in 1.9, she throws fireballs at you and does splash damage if you get close to the portal. The Wither you just spawn him in a cave & gap. He's pretty easy lol.
I think she's harder for no reason other than the new iron bars around some of the crystals which force you to climb the towers.
Surprisingly the Wither is actually winning in votes but yet so many comments for the Enderdragon lol
Whenever i see this threads title i laugh a bit Oh me and my immature thoughts Anyways, The dragon is harder imo, it's harder to get to, and harder to fight, especially with the crystals healing it, and now in the new update, the crystals are blocked.