The best class for a reach weapon? The knight, hands down.
His 3rd level ability bulwark of defense is the key. You run up to an opponent and hit him with your reach weapon. Now, he takes a 5 foot step on his turn to attack you. EXCEPT!!! Bulwark of defense means he cannot take a 5 foot step, he has to take a 5 foot move to get to you. That provokes an AOO. Not only that, he only gets one attack against you.
On your turn, you take a 5 foot step back and full attack. Rinse and repeat.
His 3rd level ability bulwark of defense is the key. You run up to an opponent and hit him with your reach weapon. Now, he takes a 5 foot step on his turn to attack you. EXCEPT!!! Bulwark of defense means he cannot take a 5 foot step, he has to take a 5 foot move to get to you. That provokes an AOO. Not only that, he only gets one attack against you.
On your turn, you take a 5 foot step back and full attack. Rinse and repeat.