If your cabe runs are approx. 12' (15'-16' is also fine) try single runs of Neotech 22 gauge solid core copper sheathed in Teflon.
You will require 4 single runs for a pair of single wired speakers.
I'd order them a foot (or two) longer, per run, as you will end up trimming/refreshing the ends over the years.
I've been using 47 Labs OTA speaker cable for 20+ years and I'm on my 2nd pair only because one of our cats damaged/partially stripped a pair.
Use bare wire ends sans connectors.
DeKay