What are the short term (3-5 years) and long term (5-15years) advantages/disadvantages traditional vs. Computer managed investment firm.
If by "computer" you mean index: traditional funds charge much higher fees. That means they have to do that much better than the index funds just to be equivalent, and preferably better. In many cases they really don't, making the index fund the winner.
BUT that's a generality, which may not aply to any specific fund or funds. Do your homework.