I have used MSV Co-Focus 1.18mm in my 18x20, and it was great... so a thicker gauge version would also do well. I have used hybrid set-ups with Babolat Origin in the Mains and a round poly in the crosses. RS Lyon would be great, as would MSV Focus Hex +38; Tier 1 Black Knight, Tour Status, Ghostwire; Grapplesnake Tour Sniper, Alpha, Tour M8 (fantastic string), and many other Grapplesnake strings. I will be using Head Syn Gut PPS as part of the hybrid set-ups, as well as Gosen OG Sheep Micro, Gosen AK Control 17, and AK Pro CX 1.24mm. You could look into Kirschbaum Pro Line Evolution and Pro-Line X; Weiss Cannon Red Ghost, Silverstring, and Scorpion; Ashaway MonoGut ZX.
Hopefully, that is enough.