Meh I find him ok challenge. My lowest beating him was in mid 40's on my second to last time through the game on the PSX remake.

Personally I say X-Death was harder (granted I was like 20 levels too low to fight him when I did it and he could nearly one shot me at will. >.>) And FFVIII's last fight.

But beyond those I would say IV would rank amoung the harder ones. Much easier then some *coughFFXcough*