Neither. Bare wire.

@bdp24  I did chop the spades off my Clear Day speaker cables. 😉

Bananas provide better contact and are lower mass than spades; bare wire comes loose. Crimping is better than soldering for the same reasons.

Obviously the bare wire method wouldn't be applicable to some of the more exotically constructed cables. I use solid core silver or 14 gauge OCC copper and have never found it to "come loose." I do however go over connections and ensure tightness. Anyhow, I imagine it can only improve sound with one less connection point.

bare wire comes loose.

Spades are hard to work with when working from the front of a unit by feel to the back. Bananas work well for that. 

Spades typically can be of higher quality metal--prefer crimping over solder.  Mate that with the Cardas CPBP single knob binding post--ultra snug connection that will NOT come loose!  For my money, the best connection out there.

CPBP Single Knob Binding Post