Bec de corbin
It's a good choice when you play siege a lot. In narrow corners and hallways, you won't get stuck too often with the Bec. I personally do not like it though, it's a bit weird to forsee when the hit will "connect", i.e. deal its damage or be blocked. The timing on this weapon is very strange, but on the other hand, that's a unique selling proposition. Try it yourself, it is a matter of taste.
The Long War Axe is one of my favorites among the polearms. It has the bonus against shield thingy, is not unbalanced (unlike the Great Long Bardiche) and it is less mainstream than the Great Long Axe. It also connects faster, so you hit earlier than with the Great Long Axe and the enemy does not have that much time to block.
The Glaive is another badass alternative. It looks very dangerous, and it is. Fallen_Wayyyne has been using it for a while, and STR_Nockeyboard. Both scared me as hell, I had no chance against them. They are good players and picked the Glaive, a wepaon that's very disgusting to fight against. You have a hard time blocking things and not getting stunned, and the worst part is that the Glaive seems to be a weapon that is sometimes even faster than your onehander or twohander. If I played polearm, I'd go for Glaive.
The Long Hafted Blade - regardless of the stats - feels like a mixture between Bec and Glaive whenever I pick it up from the ground. Longer than the Bec, shorter than the Glaive. This weapon also connects pretty early and is a solid alternative to both.
The Long Hafted Spiked Mace is your weapon of choice if you want to make people fall on the ground and hit them (knockdown). The blunt damage also penetrates armors very well.
Slower and more powerful with crushthrough instead? Long Maul.
If it has to be a spear, I'd recommend the double sided lance. Fast as hell, it surprisingly has 4 attack directions, which confuses lots of enemies. The pierce damage kicks ass.
I hope that helps!