But is there a reason to use the tri-slosher over the regular slosher, more specifically the slosher deco. I mean I'm pretty sure a splash wall is better than a disruptor, and you have a Kraken instead of a bubble, two things that both give you super armor. And besides it's not like the range is any better (it's shorter), and both versions are a two hit kill. These reasons, specifically the range, is why I also think that the sloshing machine is worse than the regular slosher, even with a bomb rush.
Just like Leronne said, the Slosher is not always better than the Tri-Slosher. The Tri-Slosher is clearly a more mobile weapon as you can get in someone's face and with a three way spread of ink, its like a Sploosh in terms of how easy it is to hit your target as opposed to a straight line of ink from the Slosher. Also, the kit is up to preference as the Disruptor helps cripple and gives you a chance to charge in. Again, like Leronne said, the Bubbler is a different kind of invincibility, one that is far more superior to the Splash Wall, judging how the Bubbler is a special while the Splash Wall is a sub weapon. The Tri-Slosher also beats the Slosher in speed in exchange for range but both get the reliable 2HKO regardless of direct hits or not. The Tri-Slosher is more close combat suited while also being offensive in the way that it can disrupt enemies and charge while the Slosher is more of a defensive option compared to the Tri-Slosher, as it has range and it can play more safe, throwing Splash Walls and shooting Inkstrikes or turning into a Kraken or burst bombing enemies when approached.
Even though I know its your opinion as you main a Slosher Deco while I might be biased because I main the Tri-Slosher, all weapons that Nintendo have made for Splatoon are better than another in one way and worse in another. So basically, all weapons are equal in how well they can be used while the gap might be due to the lack of players excelling with the weapon due to a higher learning curve.
However, some underestimated weapons that I personally think have great potential are (again :p) Rapid Blasters, Custom Splattershot Jrs, and the .96 Gal.
The Rapid Blasters have about the same speed as the Luna Blasters, contain a great range and has a decent blast box when aimed correctly. Stacking some damage up is key but with proper positioning, the Rapid Blasters could really tear up the Tower Control meta. The same goes for the Rapid Blaster Pros too as they have a far superior range, and a 2-3 shot kill when positioned right. The Deco excels against his brother as in my opinion, the Disruptors and the Killer Wail help to change the tide of the game by breaking up clusters and isolating players by disrupting them.
I've seen many Splattershot Jrs, but I haven't seen many of the Custom variants. The Splattershot Jr is an all around great weapon with bombs but maybe its my love for Disruptors but I feel that the cripple will benefit the Splattershots even more as they are close ranged shooters. Also, another Echolocator is always good as with the newest update, more players have been changing up their abilities, swapping out Cold-Blooded.
The .96 Gal is severly overshadowed by its meta changing brother, the Deco. The Deco is one of the most used weapons along with the Tentatek, Octoshot, and the .52 Gal. However, if you ditch the reliance on the Splash Walls and invincible Krakens for one moment, the vanilla variant is a beauty. Along with its already great turf coverage, the Sprinklers help make the battle field more your team friendly and is even great as bait against players. Also, they pop the Rainmaker bubble fairly easily when you need a teammate to guard it the most ;).
The Echolocator once again is a very strong option as even with Cold-Blooded players, it allows your team to be on the guard and know what to expect. I have played the .96 Gal in the S ranked lobbies and ever since I picked it up, I have started to see great success.