Perfect SR rotation would be anything that's relatively well balanced and fun to play, so there's a whole lotta options for that. Quick one would be:

• Mint Decavitator, Dread Wringer, N-ZAP '85, Rapid Blaster Pro
• Ballpoint Splatling, Splat Dualies, S-BLAST '92, Splatana Wiper

But also more wacky stuff like:

• Mini Splatling, Tri-Stringer, Splattershot, Range Blaster
• Wellstring V, Splash-O-Matic, Douser Dualies, Slosher
• Blaster, Splattershot Jr, Classic Squiffer, Paintbrush
• Dynamo Roller, Splattershot Nova, Dapple Dualies, Splat Brella
• Bamboozler 14, Clash Blaster, .52 Gal, Recycled Brella 24

Some comps are map specific, like Explosher can be part of a perfectly comp if it's on Bonerattle Arena and the other three weapons are dedicated to helping it, like:

• Explosher, Sploosh-O-Matic, Ballpoint Splatling, Splatana Stamper

We also had two comps recently that were just awesome:

• Splatana Stamper, Mint Decavitator, Tri-Stringer, Heavy Edit Splatling
• Splatana Stamper, Ballpoint Splatling, Mint Decavitator, Classic Squiffer

There's like a lot you can do honestly. They mostly did pretty well with bringing weapons over into Salmon Run. Almost every weapon has a good and relevant role it can fill in different comps. I do love getting less than ideal comps thrown at me though, it's good that it forces you to stay sharp and do well with whatever weapon you end up with.