Atgeir is my favorite weapon. I was using maces for a long while when I started playing the game, but I got tired of the knockback always knocking things back out of range for combos or finishing them while stuned. I tried sword/shield and atgeir on plains to figure out what I preferred and Atgeir all the way. The pierce damage is super nice and if you time your parries with it you can smash anything pretty easily. If you do ever get swarmed or overwhelmed you have your secondary attack to give you some space. As others have mentioned it makes ticks super easy. The stun function when you hit mistlands tier makes the best weapon even better.