I try to wield a variety of different weapons, as I believe that any weapon can be considered good with the right team setup and skill (two highly coordinated Undercover Brellas can easily mow down single targets lol).
But currently my favorite weapons to use would be (but are not limited to), for each weapon class (in Splatoon 3 to avoid confusion)
Shooters: N-Zaps and Jet Squelchers
Rollers: Krak-On Splat Roller
Chargers: Snipewriter 5H because I cannot aim using a normal charger, though I consider using the Bamboozler more often
Sloshers: I have not touched a slosher in a long time, but I would probably say Slosher Deco and maybe Tri Sloshers
Splatlings: Heavy Splatling Deco and Zink Mini Splatling
Dualies: Uh, Custom Dualie Squelchers, maybe
Brellas: Tenta Brella and Undercover Sorella Brella
Brushes: Octobrush and Painbrush Nouveau
Blasters: Rapid Blaster Deco
Stringers: None, I am consistently bad at using stringers
Splatanas: Given the choice between the only two options currently in the game, Splatana Wipers