ok you people seemed a little confused

Smackdown series = bad.
Gamecube series = good.
And i will now tell you why:
1. Smackdown announcing is worse then the music.
2. Smackdown is unrealistcly fast paced.
3. In smackdown if you get hit with a chair you dont fall down.
4. Smackdown story mode lasts abut 15 minutes.
5. WMx8 path for titles isnt good either but still a little more chalanging.
6. Smackdown graphics arnt nearly as good.
The run down:
Graphics:
Smackdown has many jaggies and hasnt made a vast improvment onto the PS2.
X8 has better graphics, although still has a un-realaistc feel, still topping smackdown though.
Winner: x8
Matches / Modes:
Although Smackdown might not be the greatest in the gameplay department it has many modes and matches, X8 has a lot but comes no where near SD.
Winner: Smackdown
Gameplay:
X8 runs away with the victory here with a more re-alistic stay-down time but keeping a grapple system similar to SD.
Winner: X8
Sound:
Smackdown wins, but i still dont like smackdowns sound.
Winner: Smackdown
Lasting Appeal:
Pretty much equal here, but unless you have someone to play smackdown with there isnt much along the lines of an actual single player mode that takes any time. X8 has path of champions and many belts to battle for.
Winner: x8
Overall Winner: WMX8
(this post was my opinion)