Here are my favorites and reasons...
Human - +2 Str, polearm fighters are feat intensive, so bonus feat helps a lot, you end up with great defenses since you're paying attention to Str/Dex/Wis.
Thri-kreen - +2 Str/Dex, extra speed is nice, good multi-mark options
Eladrin - +2 Dex, teleporting to where you need to be is great when you have reach. Eladrin Soldier saves a feat. Eladrin's Challenge is nice if you don't have access to dragonmarks.
Goliath - +2 Str/Wis, resistance works well when you leave things prone at your feet, great PP choice.
Dragonborn - +2 Str, breath is a good multi-mark, Draconic Arrogance
Longtooth Shifter - +2 Str/Wis, if you focus on multi-attacking and off-turn attacks, the bonus from longtooth shifting can add up respectably.
Elf and Half-orc will work also, as far as stats are concerned, but I don't feel they offer sufficient interesting benefits otherwise. Half-elf (or Revenant half-elf) might be interesting depending on your dilettante, though nothing jumps out at me right now. And there is undeniably great support for dwarf fighters, though nothing specifically polearm related.