basicaly you need a bite indicator to show if the fish is swiming towards you as your alarm will only sound if the line is pulled forwards. having a bobbin, monkey climber or swinger will keep tension on the line and if the fish swims towards you the alarm will still sound.
as to what is best i thinks that down to a personal choice. monkey climbers are a bit limited in the action but wont move about in high wind giving false bites. i am more than happy with my bobbins though my mate swears by his swingers