warrior / monk etc. got a simple problem: a) melee and b) if I charge, my toons continue following and break their current cast. If I stop follow before charging I can run back to get them back in follow distance.
That's why I don't want to quest with a combination of melee and range dps. So I will choose a druid which can be a boomkin or keep the group alive in AOE situations with HOTs and it can be a tank for LFG

hybrid healer+dps:
thought about a lot of combinations but in the end I won't choose a mixed team.
Mixed teams will be more effective with buffs etc. but I will try to keep my setup simple and clean.
And for healing, you got 2 choices:

a) dedicated healer which heals the group
b) everyone can heal and keep the tank alive with a sh*tload of HOTs while they DPS

I'll take option B

Therefore I need a dps healer with HOTs:

Shaman: no HOTs (except in heal specc). Totems got a Cooldown now.
They had been my fav. in WOTLK but they lost too much power

Druid: lovely hots, they could stay out of moonkin and keep DPS and healing as a caster.
But I will loose a lot of DPS and got the lunar/solar phases and all the additional dps stuff
must be casted via mouse on the ground

Priest: disc priest: passive heal via atonement, can shield and renew, can DPS.

therefore: priest.