I can't recall having *ever* seen solid "speaker wire." (I *could* be wrong.)
Generally speaking, if it's subject to ANY flex, go with stranded.
At audio frequencies, to me and probably you, it won't sound any differently. Some people SWEAR they can hear a difference between lamp cord and oxygen-free wire. I can't hear a difference. Can you?
I use lamp or zip cord exclusively. My wallet likes the difference.
Depending on the distance from amp to speaker and how loud you play the sound, ordinary lamp cord or zip cord may be too thin. Also you can get away with slightly thinner wires if the amp output impedance is higher.
The only advantage I can think of for oxygen free cable is that it doesn't turn ugly green with age and oxidation of the copper as fast.
Hmmmm... I've had this analyzed by XRF (X-Ray Fluorescence) Spectrometry. The green color is due to the copper reacting with the chloride from the PVC. Unsightly but it only goes down a few microns. The rate of formation of this color is dependent upon the particular PVC used, the temperature, the humidity, the nature and amount of plasticizer, etc. Almost all wire for speakers is OFC according to some discussions I've had with Madison, a major producer of copper wire. Regardless of whether the wire is OFC or not, the rate of oxidation of the copper with oxygen is for all intents and purposes, the same.