To terminate.. or not

It depends on your requirements. The best connection is to solder because it eliminates the #1 problem of contact reliability, which is tension force. Obvisouly soldering is not always an option and you must connect meachanically. In which case, bare wire offers the best reliability. If it is a semi-permanent connection, like at the speaker, then there is no reason not to use bare wire. The problem with bare wire is that strain releif is next to impossible. If you are going to plug/unplug often, like at the amp, then bare wire can stress, fray, break. In which case, you probably need a connector for strain releif as well as convenience. Going back to rule #1, select a connetor that offers tension force. That would be a locking banana.

I hear so many people say that spades offer the best quality. But I never hear a reason why. My experience has been poor. Can someone please tell me one good reason why to use spades?

Now that we are on the topic, why don't they put lock washers on bidning posts? That would apply tension force to hold both bare wire and spades in place.

Yes, surface area makes sense. But do you really get contact over the entire surface? Both the spade and the binding post are probably not as flat as they may seem to the naked eye. The result is contact only on highest spots of the top surface and the lowest spots of the bottom surface. But if you add a lock washer on top of a star washer, now you are guaranteed surface area coverage plus tension force.

You can shield the entire cable to reduce radiated EMI except for the termination. So how do you reduce radiated EMI at this point? The answer may be geometry of the termination. You probably want something flat and wide because it dissipates the magnetic field versus something long and narrow that concentrates the magnetic field. This is one possible reason for a spade over a banana.

Actually, I was talking about EMI radiating out of the binding post and onto adjacent compnoents/cables. Speaker cable doesn't need to be sheilded because it has low impedance and high current.