Bare wire is the best electrical connection. It's recommended to cut off an inch every year or two years to refresh the connection with the speaker and amplifier terminals. Tinned bare wire with solder will protect the bare ends from oxidation and strands from braking up or causing accidental short circuit. Before tinning and before tightening the wire to the terminals it's recommended to clean it with isopropyl alcohol because human skin leaves a greasy film that further oxidizes the metal.
If you often swap gear, bannana/spade termination is more practical and also a better visual show. Soldered spade ends are electrically a better connection than screw-on bannana plugs.
Cutting off an inch of each cable end once or twice a year is also recommended for all types of screw-on plugs, not for soldered ones but no harm if those get cleaned with Servisol and alcohol.