What animation method should I use?

Now I want to create 2D animation and I want to do them in flash, but what method should I use that, while not Disney, and obviously cheap, but is easy on the eyes and even endearing, because at least the episode can be good. (kind of like South Park to me)

1. Frame by Frame animation, that doesn't use a lot of frames, only one inbetween frame... between the extreme frames. It might make the animation unfinished.

2. Motion Tween animation that uses models like puppets. Very common in old Newgrounds animation and also used in Harvey Birdman and My Little Pony. Problem I have is it can look a bit stiff.

3. A mixture of both. Sometimes the drawings are different, but they are moved by motion tween. Sort of like this series. https://www.youtube.com/watch?v=Yv2DkYRyH3Y&index=7&list=PLE3ED0EFA56BD67DA This might makes things a little inconsistent, but again, none of us may care.

i'd recommend frame by frame animation, even if it seems a little more labour-intensive. it looks a lot less cheap.

Frame by Frame is much easier but needs more work in the long run.