I haven't experimented myself, so I am just relaying information from two friends who are high end dealers. For convenience, dealers love Banana plugs because they change out gear all of the time. However, neither use banana plugs because they find spades to be substantially better.
I actually got to hear a pair of small spendor speakers outfitted with a pair of extremely large binding posts from Australia that where silly expensive (sorry, I can't recall the brand name). The matching spades were thin, but also really big so they had a large contact area that corresponded with the large area of the binding posts. The improvement in dynamics and bass response was shockingly big -- you could not imagine that these were the same speakers as the ones equiped with OEM spades.
I actually got to hear a pair of small spendor speakers outfitted with a pair of extremely large binding posts from Australia that where silly expensive (sorry, I can't recall the brand name). The matching spades were thin, but also really big so they had a large contact area that corresponded with the large area of the binding posts. The improvement in dynamics and bass response was shockingly big -- you could not imagine that these were the same speakers as the ones equiped with OEM spades.