I've put quite a few hours into Splatoon, mostly dedicated to chargers. And I've got quite a bit to say about each. Though it seems a bit backwards, I play a pretty offensive charger. I like to get right out of range of my opponents, pick them off, and keep pushing until they're pinned to their spawn. Well, that's the ideal situation, anyway.
Given this description, you'd probably think I'd favor the Squiffers. But they're my least favorite, mostly due to range. If they're going to be outranged by Splattershot Pros and Jet Squelchers, they could've lessened the charge time by about 12 frames. The Classic Squiffer has great synergy with it's point sensor and bubbler, but with such limited range, I don't see why you wouldn't use an automatic if you want to get up that close.
The E Liter 3k was the first weapon I really put a lot of time into learning, and probably the weapon I've spent the most time with overall. Let me just say, I LOVE this weapon, or perhaps the idea of it. After I realized you could stack damage to cut down on charge-to-kill time, I was all over this weapon. Those few times where I have pinned an enemy team to their base, I was using this weapon on usually Port Mackerel or Walleye Warehouse. The range is ridiculous, and even if you can't get a shot on the enemy, you can implement some scare tactics and pin them to a corner at the sight of your aiming laser.
While I think the Custom is the better of the two in a cooperative team setting, I've grown quite attached to the standard E Liter. Burst bombs are a great utility for this weapon. You can quickly ink walls to climb to sniping areas, quickly make a nest in enemy ink, take out a nearby foe, or run away from them if they get too close. I've had quite a bit of success in puddle jumping away from bad situations while actively making the puddles as I go with these. Also, the Echolocator is such an obvious plus, and one that helps your teammates immediately.
The Custom handles the short range enemies even better with the Kraken, but that requires having the special charged, which you won't always have. In a setting with random teammates, I'd rather have the burst bombs. Definitely consider special charge up if you use the Custom, for your own safety. The real advantage of the Custom are the Beakons. Being able to swap quickly between two vantage points and helping your teammates quickly get to a safe location deeper in the field is a great thing.
My issue with the either E Liter is that the ink consumption is absolutely disgusting. Even with an Ink Saver main and a sub, you can still barely manage 4 shots on a full tank. You will be spending so much time recovering ink, that even though you have the option to make it an offensive weapon with Damage Ups, you'll end up running out of ink at crucial moments very, very often. As much as I love it, it's a defensive weapon, needs a lot of Ink Saver support, and it's not suitable to my playstyle. This is why I've recently revisited the Kelp Splatterscope.
I've seen someone say once before that the Squiffer and E Liter both reach a little too far into extremes, and it's a notion I can somewhat agree with. They're both situational, depending on team composition or map, and receive severe nerfs in exchange for their advantages. The standard chargers are a good balance between the two. I don't feel myself hurting for range or running out of ink, unlike the other two. The Kelp Splatterscope has become my recent weapon of choice for this reason.
I miss the range of the E Liter sometimes, but the Splatterscope covers 85% of everything I needed to do with the E Liter (except for Arowana Mall, where it's more like 60%). I really don't care for the scope, in fact, I think I was more accurate with the E Liter, but I like to have that extra nth of distance compared to the standard. I've seen some concerns about peripheral vision with the scope. If you're going to play offensively, as I do, you should only take aim once you have a target, and know where they will be. If you're playing defensively, you should be watching your map at every opportunity.
I choose the Kelp brand because I like the sprinkler for ranked. I don't have much of a preference for Turf War. The sprinkler is good for putting in tricky locations to help hold the hill an extra second or two when it gets overrun. Obviously it's good as a distraction, and a one-hit body guard as well, but it's also a great way to charge your special when you get splatted. Just throw it on some uninked turf while you're swimming where you want to go, it helps a ton. And on that note, the Killer Wail is a nice option to combat E Liters when I'm outranged. If I see one on the opposite team, I'll hang on to my Special until they find a perch, then fire it at them. If I miss, I chase them down and snuff them out before they become too much of a problem for my team. I try to repeat this until the feel forced to play offensively, where they often fail.
I've taken the time to record and analyze frame data for the charge-to-kill time for the 3 charger types and how damage up improves them. One Damage Up main and 4 subs puts my Splatterscope at the same charge-to-kill time as the Squiffer. So that's what I'm currently using in ranked. I'm working on a video now to compile all of this frame data, and hope to be able to share it with you all in the coming week.
So which is my favorite? Kelp Splatterscope at the time of typing all of this. But I think an offensive Splatterscope and a defensive E Liter make a fantastic team.