Are spears or polearms better? what are the pros and cons of each?

The pro's and cons.. hm.

Spears=

You stab, you do more damage
You smash you do less.

pole arms=
You stab, you do less damage
You smash you do more.

Lol.

Out of 3 attacks, you will probably smash 2 times and stab once. Spears do a bit more damage than polearms, but you smash more than you stab, so it kind of compensates.

ok, but other then the stab and smash damage factor, is there any other differences? Is there any other reasons to pick one over the other?

If you like the look of spears of polearms better...

Well, in 3rd job there is a skill that stabs 3 enemies 3 times, and another skill that smashes 6 enemies once. The 3 stabs with spear is a bit better than one smash with polearm, so spears are a bit more popular in 3rd job.
Some people go Hybrid- that's when you use polearms in 1st and 2nd job (due to the 2 smash- 1 stab thing), and then switch to spears in 3rd job.

In 2nd job polearms are better because of the slash/stab ratio, in 3rd job the majority of people prefer spear because of its main attack. You could go hybrid by maxing both masteries and getting booster in both, that way you could use polearms in 2nd and spears in 3rd. In my opinion, you should just use whichever weapon looks the coolest, seriously, who cares how high level you are if you aren't sexy?

also.

Final attack sucks balls. You can go hybrid.

I went full spear, because i dont like crusher, but you can easily go spear and pole arm. Final attack is useless after level 70.