Saying Secret of Mana is one of the worst games for the SNES is a bit of an exxageration. Secret of Mana objectively had excellent gameplay, and although the Tiger was easily the hardest battle in the whole game, I wouldn't go as far as to call it impossible. Patience is always rewarded...

Anyway, some SNES games you should definetly avoid:
Space Ace
Dragons Lair
WarpSpeed
Kablooey
Most movie licences(excluding Batman Returns)
All Street Fighter 2 clones