Either spades or bananas work well as long as you realize the limitations of either. However, I tend to prefer bananas for some practical reasons, so I'll make a pitch in their direction.
1. Easy to install and remove. Does not require crimping tools (that properly fit the spades being used) or soldering (the best way tro attach spades to wires).
2. Available to easily fit either standard or large gauge wiring, just like spades.
3. Available in locking form, gold plated, different colors for channel coding, single, dual.
4. Color coding is especially useful for amplifier connections on theater/multi-channel or multi-room systems.
5. Contact surface area can be larger than some smaller spades; depends of course on posts they're connected to. One could argue that a well made banana plug offers better contact area to a post than most modern (US format) 120vac plugs and receptacles. (Another example-- Ever look at some of those IEC plugs/sockets, and note how little actual contact area there is? I find it kind of scary that some of these items get UL approval.)
6. Dual bananas on speakers prevent or greatly reduce the chance of shorting amplifier outputs if you unplug them from a speaker and forget to turn the amp off first, since it inherently holds the leads apart.
7. Makes trouble shooting faster (swapping channels on amp or speakers).
Last comment and then outa here-- want good plugs cheap? Check out Pomona, the peeps who make all the test equipment cables and connectors and such. They make many different single and double banana plugs/jacks/posts, all very well made and selling for way below the "audiophile" plugs that look suspiciously like they were sourced form same and just marked up about 300-500%.
Available in nickel or gold plate, usually also in different color bodies which can be handy for multi-channel amps, as already mentioned. No, I own no stock in the company, but I've used them in installations (and on my bench) for over 20 years with near zero failures/problems.