Bananas rule, spades drool. End of discussion.

I agree with Erik having found a loose spade or two. I will second locking bananas as the best solution and one that I believe bumps up the surface area in contact with the speaker. The spade issue has always stuck me as something fairly easy to fix with a spring or lock washer, but then there will we will need 7n OCC gold plated versions of those too.

@hilde45 - I’ve never encountered one in the wild.  I have no way of statistically examining a sample of every connection ever made to a speaker.  All I can do is talk directly about my experience and I've never had a banana come loose just because. 

I can't say that about spades, at all.

I have seen the cords pull out of a banana plug at a dealer, but that was nothing to do with the banana to speaker side, and I'd expect it had more to do with the wear and tear dealers put on their cables while switching demo speakers.

I've had only one connection ever get totally loose and it involved a spade connection.  I currently run banana jacks.  That one time was pretty funny because I totally missed what happened and my travails involved an incredible coincidence.  I almost never fiddle around with my system so I would never expect a loose connection.  I do move my interconnect from my speaker amp to my headphone amp when I want to listen to headphones.  On this one occasion, I forgot to switch the interconnect back to the main speaker and I turned on the mono bloc speaker amps.  When I noticed this error I turned the amps off and made a quick switch and I did not wait before turning the mono blocs back on.  I saw a flash in the rectifier of the right side amp, and then no music from the right speaker.  I turned the amp off, and not wanting to risk any further damage, I took the amp (Audio Note Kageki) to my local dealer.  At the dealership the amp worked flawlessly.  I brought it home, hooked it up and it didn't work.  That was when I actually tried to diagnose the problem as not involving the amp.  It turned out that one of the spades to the right speaker was loose, but because it was fitted into one of those modern binding posts with a plastic hood to protect people from exposed wire, the speaker cable hung in place as though it was connected.  The odds of the wire slipping off just before I saw the unrelated rectifier flash was extremely small, yet it happened and threw me off.

With you on this one.  Bananas are much more convenient  to install with our ever increasing cable sizes.  Especially with how close makers design their speaker posts so darn close together.  Give us some space guys.  No matter how tight you tighten smooth gold, copper, silver or rhodium spades they tend to want to spin risking a potential contact with a neighbor. I cracked a speaker post base trying to keep spades from spinning.  Haven’t suffered SQ using bananas that I can notice.

+1 @erik_squires totally agree. I used to be a bare wire advocate but after going to banana connectors I’m a believer.