I vote all of the Hero weapons first of all, I adore their futuristic looks. I think it's especially cool that the Hero Roller Replica has little spots on it that light up. Such a nice touch <3
The Tempered Dynamo Roller has those really soft, painterly blue and purple hues that I love... The Berry Splattershot Pro is like a rainbow, I wish I could shoot actual rainbows out of it, lol. The Grim Range Blaster's green color scheme fits its name; really gives it an extreme, horror-type of vibe if you really sit and imagine it that way, lol.
My two favorite weapons have to be the Hydra Splatling and the E-liter 3K Scope, though. The former is just this gigantic, imposing cannon with bright flashy reds to make it stand out; the Custom variant's sticker adds a splash of color that brightens it up even more. I love the fact that the E-liter is a gas tank with a long nozzle attached to it; the scope really completes the look of the weapon, imo. And I just love the sounds that both of them make. They're both very powerful as well as uniquely designed, I love them a bunch <3