An important feature u may require with traditional key frame animating is onion skinning or being able to see multiple layers with different opacities..
what ever package floats your boat can all perform the same tasks with various degrees of workflow repetition and construction.
An alternative is to use my free 3d to 2d render script.
You deply your charactters by making them 3d and then using the script to export the 2d cells in the required angles and positions.
This is less time consuming in some ways but can lose a traditional feel unless the 3d models held a style or genre thats appealing.
You can use much higher poly models for this method as the end result is just 2d.