What's the best 8 directional movement method

Under the application properties, there's a tab for runtime options where you can change the default controls to let the player use WASD instead of the arrow keys

For the default 8 direction movement, if you're using the "stop" movement for collisions against a backdrop, that should be less bouncy than using the "bounce" command. The only thing I can think of is making the object's movement animation changing the collision mask of the active which might make it bounce if some frames have a bigger sprite than the others

I suggest you read up on fast loops, and once you understand that search for examples of custom 8 direction fast loop movement. There are several on the forums here, and around the net.

It's impossible to get pixel perfect movement without weird bounciness on the built in movements unless your character/s is/are only moving 1 pixel per frame. What happens is that if you move more than that, you are jumping that many pixels per frame, so you can move past an object before the engine detects that you have overlapped it (or it wont detect it at all if you're moving too fast, because you will essentially teleport past it). With fast loops, you can move multiple pixels and check for collisions on each pixel moved before the next frame is even rendered.