I am totally on Cap's side. He's all about saving others without government interference and I think his theory is very logical. Government can sometimes be very corrupt and abuse their authority by taking advantage of the citizens for their own benefit. Cap just wants to avoid all this and just save people when they need saving. He's the best!!!
Tony Stark knows that you simply cannot have a desperado, wild group of uncontrolled superhumans that can cause more damage than an atomic bomb. There simply needs to be accountability.
At any rate, the Sekovia Accords were pretty much PR for the shame-faced politicians because the Avengers are more powerful than the government and could take them anytime. Yet by not signing, Cap made the world government his enemy, which simply makes things harder, especially when he didn't have half of the Avengers on his side. Stark was right. There needs to be accountability for this dangerous group of superhumans.