Honestly, his techs aren't that good without his kinjutsu.
He's not immortal and he can't use Edo.
What does that leave him with? Summonings, which Jiraiya beats him at, Taijutsu which he isn't that good in, sealing jutsu, which Minato beats him at...
My point is Oro excels in forbidden techniques. Remove those and he isn't -THAT- strong.
-_- have we seen his jutsu?!? He was candidate ahead of anyone else, prior to his forbidden jutsu. We've only seen him in ONE serious fight while capable of using ninjutsu and that was against the 3rd Hokage. Unfortunately, he wanted to show off his ability to perform Edo and hurt the 3rd Hokage emotionally.
The fact is, we've seen less from Orochimaru than anyone shinobi in the series, as his only hand seals have been Edo or wind release, where he wanted to test Sasuke's strength.
So please, don't sit there and try to judge someone who hasn't shown us anything to really base judgement. As he was credited to rival the 3rd Hokage and in the databook had knowledge of jutsu that exceeded Kakashi. Just sit and wait, you sound like a hater.
Lastly, you are very misinformed, snake>toad and Minato's knowledge of sealing all comes from his wife. Orochimaru in fact has displayed more sealing ability than Minato in part 1 alone.