The pitch fork takes only 1 slot, has good pierce damage but is very short.
The peasant scythe is quite long but has bad damage potential.
The red tassel spear is fast and has very nice pierce damage. It is sheathable and it does not appear in the back (surprise! surprise!). It is still a bit short.
Personally, I rely on the trident. It looks peasant but is a good compromise between length and damage.
They are all shorter than lances, so you can get owned easily if you don't pay attention. If you want to have a reliable anti-cav spear, you have to choose something that cannot be sheathed (pikes, awlpikes...).