For fun and actual comparison with your game play. The further you go down the list, the less you should be using that attack. Attacks in E tier should NEVER be used. Grab releases not included for what I hope are obvious reasons. Attacks aren't ordered within the tiers.
S Tier:
Fortress
A Tier:
Jab
Aerial Klaw
B Tier:
FTilt
FAir
C Tier:
Ground Klaw
Firebreath
DTilt
UTilt
UAir
BAir
Down Throw
USmash
D Tier:
FSmash
DSmash
Dash Attack
NAir
DAir
Bowser Bomb
Back Throw
E Tier:
Forward Throw
Up Throw
S Tier:
Fortress
A Tier:
Jab
Aerial Klaw
B Tier:
FTilt
FAir
C Tier:
Ground Klaw
Firebreath
DTilt
UTilt
UAir
BAir
Down Throw
USmash
D Tier:
FSmash
DSmash
Dash Attack
NAir
DAir
Bowser Bomb
Back Throw
E Tier:
Forward Throw
Up Throw