Some elaboration on why people are puzzled by someone else not liking polearms for martial classes might be reasonable. I will attempt one such summary, but my 5E is imperfect, so please jump in with corrections.
Standard glaive or halberd does 1d10, but also have reach and thus 10 foot range, and also heavy.
Polearm master gives you a bonus attack that does d4 damage, and it adds an opportunity attack when enemies enter weapon reach.
Sentinel adds that if you hit something with an opportunity attack then its movement speed is set to 0, and creatures that use disengage action still provoke opportunity attacks.
Great weapon master gives 1 bonus attack on kill or crit per turn and it allows you to take a -5 to hit for a +10 to damage on melee attacks with heavy weapons. Note that halberds and glaives are both heavy and that the ability isn't a once-per-turn but can be applied to all melee attacks.
And of course there's also item bonus and strength bonus to all these attacks.
So what the total package ends up providing is a 10 foot reach in which everything is threatened and anyone trying to leave can get smacked and lose their movement and anyone trying to enter can get smacked and lose their movement, and a smack means 1d10 + 10 for GWM + strength + item bonus + whatever else you've got floating for the regular attacks and 1d4 + 10 for GWM + strength + item bonus + whatever else you've got floating for the PAM bonus attack. Unless you kill or crit, in which case you get full weapon dice for the bonus attack.
Now imagine this on a level 11 fighter with two additional attacks and action surge. I honestly cannot be bothered doing the math but it looks like a whole lot of damage dice. I'm not sure, however, if champion crits are better than battle master maneuvers. Someone with more experience (or more will to number crunch) will have to step in on that. But a cheeky 10 foot range pushing attack near ledges could be fun, and even just pushing straight backwards means the critter has to go back in again and take another AOO poke in the process.
I reckon the salient point is, once you have the full feat package up and running with poles, there's quite some potential for both damage output and tactical utility.
