It always depends on the player of course. any toon that a person will stick to and play is the most important toon to have. After that the standard list applies. Clerics, bards, chanters, rogues, warriors, etc etc
As for PLing/twinking. Yeah I'm all for a bit of helping, but your condition of "if you make the commitment to a new toon, and work hard to level it" is very true in my case.
I'm not interested in people who want a free ride. Who will only XP in a PL group and won't take average gear because they want to be twinked with GOOD gear. Who won't get their own gear even to fill poor slots.
I'm sure kileman isn't of this ilk, but it does good to get it out in the open.
In the applications forum there is a lowbie recruitment policy. it's kinda old but it still applies. It also applies to someone starting a new toon.
Taking ownership of your toon for it's development but through XPing and gear is the players responsibility. No-one elses.