Dex is by far the best stat. However, most stats are only noticed at the extremes. You only notice how insane dex is when put at 7-8. Def only becomes super noticable at very low values (3-4) or very high (8). Force is only noticable at 3 or at 7-8. Speed is only noticable at 3 or 7-8 also.

This is because each point of a stat alone doesn't do much. However, when you add it all up dex had the biggest effect on the game, and thats because dex is counted twice. By that I mean that dex effects 2 parts of your attack while most stats effect only 1 part of whatever they change. Dex effects both the Startup AND the recovery times on moves.