I have been playing since the initial Preview event, I believe it was called "E34e". Currently I have six characters, all of which are level 20 with a large amount of skills. These characters being a Mesmer, Ranger, Monk, Necro, Ritualist and most recently a dervish. I have a bad habit of deleting characters I didn't have time to play, like an Ele, a warrior and my first Rit.
The question I poise to any potential audiences is: how many characters are enough?
When do you reach the point and say "I love these toons and they are all I need"?
With the addition of Nightfall, there are heroes that can use the skills a player has unlocked, thus providing a new motivation to play all characters. To further the idealism of creating new characters we have the opportunity to purchase more slots.
Temptation, I do say.
Personally, my necromancer is particularly neglected. She is at Ring of Fire, but has nothing past Lion's Arch until the desert. In fact, most of my tyrians dont have the jungle. It simply was irrelevant, at the time.
So for you, what is your limit?
Take into consideration the following:
-time spent leveling
-money needed to acquire skills
-money needed for gear
-ability to find endgame content