I like getting options for base classes.
Being able to mechanically represent an (un)holy champion in a dozen different ways seems right for pantheistic cosmologies with different magical traditions and divergent orders/organizations within the same churches as well as schisms and heresies, etc.
I like the ability of 3e classes to be based on different mechanical models so those who like fiddly bits can have something like classes from Iron Heroes with their token pool mechanics while others can have warlocks or technological savants (from EN Publishing's Fantastic Science) with at will always available powers or vancian casters or recharge power models like the soulknife with their psychic strike and psionic focus mechanics from the XPH.
I personally like the low end of resource management and would like to see more warlock and soulknife style classes.