Alderaan is actually more complex than how many people go where. It's highly depending on class comp. For example, at the beginning of the game, when no points are captured, middle is the easiest point to harass and prevent caps. Ideally a tank + healer (preferably with dots) can hold out against twice as many enemy players and prevent caps long enough for the other 6 team members to capture the other two points.
From my experience, the point closest to the enemy's spawn is the easiest to take, because they only send 2, 3 players tops. Send 2-3 of your best DPS there and you're guaranteed a cap 90% of the time. The side closest to your base tends to be a little less predictable. Some times there's 0 action and it's an easy cap, other times it gets zerged. Again, marauders and sins are the best classes to send there, they can get there faster than anyone else for a quick cap, they have decent survivability in case of zerg, and they can vanish and harass, buying your team additional time to either support or cap a different turret.